From b910825a84b635414ab847a16f0a8fc4a2ec416f Mon Sep 17 00:00:00 2001
From: Cagatay Civici <cagatay.civici@gmail.com>
Date: Tue, 13 Apr 2021 16:59:08 +0300
Subject: [PATCH] Fixed #1169 - Customizable ZIndex Layering

---
 src/components/autocomplete/AutoComplete.vue  | 17 +++++---
 src/components/calendar/Calendar.vue          | 20 +++++++--
 .../cascadeselect/CascadeSelect.vue           | 17 +++++---
 src/components/colorpicker/ColorPicker.vue    | 18 ++++++--
 src/components/config/PrimeVue.js             |  6 +++
 src/components/confirmpopup/ConfirmPopup.vue  | 19 ++++++---
 src/components/contextmenu/ContextMenu.vue    | 17 ++++++--
 src/components/dialog/Dialog.vue              | 16 ++++++--
 src/components/dropdown/Dropdown.vue          | 18 +++++---
 src/components/galleria/Galleria.vue          | 16 +++++---
 src/components/menu/Menu.vue                  | 17 ++++++--
 src/components/menubar/Menubar.vue            | 16 ++++++--
 src/components/multiselect/MultiSelect.vue    | 17 +++++---
 src/components/overlaypanel/OverlayPanel.vue  | 18 ++++++--
 src/components/password/Password.vue          | 16 ++++++--
 src/components/scrolltop/ScrollTop.vue        | 22 +++++++---
 src/components/sidebar/Sidebar.vue            | 28 +++++++++----
 src/components/tieredmenu/TieredMenu.vue      | 16 ++++++--
 src/components/toast/Toast.vue                | 17 ++++----
 src/components/tooltip/Tooltip.js             | 10 +++--
 src/components/treeselect/TreeSelect.vue      | 17 +++++---
 src/components/utils/DomHandler.js            |  9 ----
 src/components/utils/Utils.js                 |  3 +-
 src/components/utils/ZIndexUtils.js           | 41 +++++++++++++++++++
 src/views/setup/Setup.vue                     | 19 +++++++++
 25 files changed, 324 insertions(+), 106 deletions(-)
 create mode 100644 src/components/utils/ZIndexUtils.js

diff --git a/src/components/autocomplete/AutoComplete.vue b/src/components/autocomplete/AutoComplete.vue
index a4d1b7d0d..745f5dedb 100755
--- a/src/components/autocomplete/AutoComplete.vue
+++ b/src/components/autocomplete/AutoComplete.vue
@@ -15,7 +15,7 @@
         <i class="p-autocomplete-loader pi pi-spinner pi-spin" v-if="searching"></i>
         <Button ref="dropdownButton" type="button" icon="pi pi-chevron-down" class="p-autocomplete-dropdown" :disabled="$attrs.disabled" @click="onDropdownClick" v-if="dropdown"/>
         <Teleport :to="appendTo">
-            <transition name="p-connected-overlay" @enter="onOverlayEnter" @leave="onOverlayLeave">
+            <transition name="p-connected-overlay" @enter="onOverlayEnter" @leave="onOverlayLeave" @after-leave="onOverlayAfterLeave">
                 <div :ref="overlayRef" class="p-autocomplete-panel p-component" :style="{'max-height': scrollHeight}" v-if="overlayVisible" @click="onOverlayClick">
                     <slot name="header" :value="modelValue" :suggestions="suggestions"></slot>
                     <ul :id="listId" class="p-autocomplete-items" role="listbox">
@@ -43,7 +43,7 @@
 </template>
 
 <script>
-import {ConnectedOverlayScrollHandler,UniqueComponentId,ObjectUtils,DomHandler} from 'primevue/utils';
+import {ConnectedOverlayScrollHandler,UniqueComponentId,ObjectUtils,DomHandler,ZIndexUtils} from 'primevue/utils';
 import OverlayEventBus from 'primevue/overlayeventbus';
 import Button from 'primevue/button';
 import Ripple from 'primevue/ripple';
@@ -134,7 +134,11 @@ export default {
             this.scrollHandler.destroy();
             this.scrollHandler = null;
         }
-        this.overlay = null;
+
+        if (this.overlay) {
+            ZIndexUtils.clear(this.overlay);
+            this.overlay = null;
+        }
     },
     updated() {
         if (this.overlayVisible) {
@@ -151,8 +155,8 @@ export default {
         getOptionGroupChildren(optionGroup) {
             return ObjectUtils.resolveFieldData(optionGroup, this.optionGroupChildren);
         },
-        onOverlayEnter() {
-            this.overlay.style.zIndex = String(DomHandler.generateZIndex());
+        onOverlayEnter(el) {
+            ZIndexUtils.set('overlay', el, this.$primevue.config.zIndex.overlay);
             this.alignOverlay();
             this.bindOutsideClickListener();
             this.bindScrollListener();
@@ -164,6 +168,9 @@ export default {
             this.unbindResizeListener();
             this.overlay = null;
         },
+        onOverlayAfterLeave(el) {
+            ZIndexUtils.clear(el);
+        },
         alignOverlay() {
             let target = this.multiple ? this.$refs.multiContainer : this.$refs.input;
             this.overlay.style.minWidth = DomHandler.getOuterWidth(target) + 'px';
diff --git a/src/components/calendar/Calendar.vue b/src/components/calendar/Calendar.vue
index 15ab9fbfb..7be749731 100755
--- a/src/components/calendar/Calendar.vue
+++ b/src/components/calendar/Calendar.vue
@@ -4,7 +4,7 @@
             :class="inputClass" :style="inputStyle" />
         <CalendarButton v-if="showIcon" :icon="icon" tabindex="-1" class="p-datepicker-trigger" :disabled="$attrs.disabled" @click="onButtonClick" type="button" :aria-label="inputFieldValue"/>
         <Teleport :to="appendTo" :disabled="inline">
-            <transition name="p-connected-overlay" @enter="onOverlayEnter($event)" @after-enter="onOverlayEnterComplete" @leave="onOverlayLeave">
+            <transition name="p-connected-overlay" @enter="onOverlayEnter($event)" @after-enter="onOverlayEnterComplete" @after-leave="onOverlayAfterLeave" @leave="onOverlayLeave">
                 <div :ref="overlayRef" :class="panelStyleClass" v-if="inline ? true : overlayVisible" :role="inline ? null : 'dialog'" @click="onOverlayClick">
                     <template v-if="!timeOnly">
                         <div class="p-datepicker-group-container">
@@ -133,7 +133,7 @@
 </template>
 
 <script>
-import {ConnectedOverlayScrollHandler,DomHandler} from 'primevue/utils';
+import {ConnectedOverlayScrollHandler,DomHandler,ZIndexUtils} from 'primevue/utils';
 import OverlayEventBus from 'primevue/overlayeventbus';
 import InputText from 'primevue/inputtext';
 import Button from 'primevue/button';
@@ -342,6 +342,10 @@ export default {
             this.scrollHandler.destroy();
             this.scrollHandler = null;
         }
+
+        if (this.overlay && this.autoZIndex) {
+            ZIndexUtils.clear(this.overlay);
+        }
         this.overlay = null;
     },
     data() {
@@ -523,9 +527,12 @@ export default {
 
             return validMin && validMax && validDate && validDay;
         },
-        onOverlayEnter() {
+        onOverlayEnter(el) {
             if (this.autoZIndex) {
-                this.overlay.style.zIndex = String(this.baseZIndex + DomHandler.generateZIndex());
+                if (this.touchUI)
+                    ZIndexUtils.set('modal', el, this.baseZIndex || this.$primevue.config.zIndex.modal);
+                else
+                    ZIndexUtils.set('overlay', el, this.baseZIndex || this.$primevue.config.zIndex.overlay);
             }
             this.alignOverlay();
             this.$emit('show');
@@ -535,6 +542,11 @@ export default {
             this.bindScrollListener();
             this.bindResizeListener();
         },
+        onOverlayAfterLeave(el) {
+            if (this.autoZIndex) {
+                ZIndexUtils.clear(el);
+            }
+        },
         onOverlayLeave() {
             this.unbindOutsideClickListener();
             this.unbindScrollListener();
diff --git a/src/components/cascadeselect/CascadeSelect.vue b/src/components/cascadeselect/CascadeSelect.vue
index af63f0826..afe097a10 100644
--- a/src/components/cascadeselect/CascadeSelect.vue
+++ b/src/components/cascadeselect/CascadeSelect.vue
@@ -13,7 +13,7 @@
             <span class="p-cascadeselect-trigger-icon pi pi-chevron-down"></span>
         </div>
         <Teleport :to="appendTo">
-            <transition name="p-connected-overlay" @enter="onOverlayEnter" @leave="onOverlayLeave">
+            <transition name="p-connected-overlay" @enter="onOverlayEnter" @leave="onOverlayLeave" @after-leave="onOverlayAfterLeave">
                 <div :ref="overlayRef" class="p-cascadeselect-panel p-component" v-if="overlayVisible" @click="onOverlayClick">
                     <div class="p-cascadeselect-items-wrapper">
                         <CascadeSelectSub :options="options" :selectionPath="selectionPath" 
@@ -28,7 +28,7 @@
 </template>
 
 <script>
-import {ConnectedOverlayScrollHandler,ObjectUtils,DomHandler} from 'primevue/utils';
+import {ConnectedOverlayScrollHandler,ObjectUtils,DomHandler,ZIndexUtils} from 'primevue/utils';
 import OverlayEventBus from 'primevue/overlayeventbus';
 import CascadeSelectSub from './CascadeSelectSub.vue';
 
@@ -72,7 +72,11 @@ export default {
             this.scrollHandler.destroy();
             this.scrollHandler = null;
         }
-        this.overlay = null;
+        
+        if (this.overlay) {
+            ZIndexUtils.clear(this.overlay);
+            this.overlay = null;
+        }
     },
     mounted() {
         this.updateSelectionPath();
@@ -163,8 +167,8 @@ export default {
                 this.$refs.focusInput.focus();
             }
         },
-        onOverlayEnter() {
-            this.overlay.style.zIndex = String(DomHandler.generateZIndex());
+        onOverlayEnter(el) {
+            ZIndexUtils.set('overlay', el, this.$primevue.config.zIndex.overlay);
             this.alignOverlay();
             this.bindOutsideClickListener();
             this.bindScrollListener();
@@ -179,6 +183,9 @@ export default {
             this.overlay = null;
             this.dirty = false;
         },
+        onOverlayAfterLeave(el) {
+            ZIndexUtils.clear(el);
+        },
         alignOverlay() {
             DomHandler.absolutePosition(this.overlay, this.$el);
             this.overlay.style.minWidth = DomHandler.getOuterWidth(this.$el) + 'px';
diff --git a/src/components/colorpicker/ColorPicker.vue b/src/components/colorpicker/ColorPicker.vue
index 54aeb6ee0..17af28f54 100755
--- a/src/components/colorpicker/ColorPicker.vue
+++ b/src/components/colorpicker/ColorPicker.vue
@@ -3,7 +3,7 @@
         <input ref="input" type="text" :class="inputClass" readonly="readonly" :tabindex="tabindex" :disabled="disabled"
             @click="onInputClick" @keydown="onInputKeydown" v-if="!inline" :aria-labelledby="ariaLabelledBy"/>
         <Teleport to="body" :disabled="inline">
-            <transition name="p-connected-overlay" @enter="onOverlayEnter" @leave="onOverlayLeave">
+            <transition name="p-connected-overlay" @enter="onOverlayEnter" @leave="onOverlayLeave" @after-leave="onOverlayAfterLeave">
                 <div :ref="pickerRef" :class="pickerClass" v-if="inline ? true : overlayVisible" @click="onOverlayClick">
                     <div class="p-colorpicker-content">
                         <div :ref="colorSelectorRef" class="p-colorpicker-color-selector" @mousedown="onColorMousedown($event)"
@@ -24,7 +24,7 @@
 </template>
 
 <script>
-import {ConnectedOverlayScrollHandler,DomHandler} from 'primevue/utils';
+import {ConnectedOverlayScrollHandler,DomHandler,ZIndexUtils} from 'primevue/utils';
 import OverlayEventBus from 'primevue/overlayeventbus';
 
 export default {
@@ -95,6 +95,11 @@ export default {
             this.scrollHandler.destroy();
             this.scrollHandler = null;
         }
+        
+        if (this.picker && this.autoZIndex) {
+            ZIndexUtils.clear(this.picker);
+        }
+
         this.clearRefs();
     },
     mounted() {
@@ -333,7 +338,7 @@ export default {
 
             return hsb;
         },
-        onOverlayEnter() {
+        onOverlayEnter(el) {
             this.updateUI();
             this.alignOverlay();
             this.bindOutsideClickListener();
@@ -341,7 +346,7 @@ export default {
             this.bindResizeListener();
 
             if (this.autoZIndex) {
-                this.picker.style.zIndex = String(this.baseZIndex + DomHandler.generateZIndex());
+                ZIndexUtils.set('overlay', el, this.$primevue.config.zIndex.overlay);
             }
         },
         onOverlayLeave() {
@@ -350,6 +355,11 @@ export default {
             this.unbindResizeListener();
             this.clearRefs();
         },
+        onOverlayAfterLeave(el) {
+            if (this.autoZIndex) {
+                ZIndexUtils.clear(el);
+            }
+        },
         alignOverlay() {
             DomHandler.absolutePosition(this.picker, this.$refs.input);
         },
diff --git a/src/components/config/PrimeVue.js b/src/components/config/PrimeVue.js
index 4b48591ad..fcd81b934 100644
--- a/src/components/config/PrimeVue.js
+++ b/src/components/config/PrimeVue.js
@@ -69,6 +69,12 @@ const defaultOptions = {
             FilterMatchMode.DATE_BEFORE,
             FilterMatchMode.DATE_AFTER
         ]
+    },
+    zIndex: {
+        modal: 1100,
+        overlay: 1000,
+        menu: 1000,
+        tooltip: 1100
     }
 };
 
diff --git a/src/components/confirmpopup/ConfirmPopup.vue b/src/components/confirmpopup/ConfirmPopup.vue
index 853080125..fb285a9ed 100644
--- a/src/components/confirmpopup/ConfirmPopup.vue
+++ b/src/components/confirmpopup/ConfirmPopup.vue
@@ -1,6 +1,6 @@
 <template>
     <Teleport to="body">
-        <transition name="p-confirm-popup" @enter="onEnter" @leave="onLeave">
+        <transition name="p-confirm-popup" @enter="onEnter" @leave="onLeave" @after-leave="onAfterLeave">
             <div class="p-confirm-popup p-component" v-if="visible" :ref="containerRef" v-bind="$attrs" @click="onOverlayClick">
                 <div class="p-confirm-popup-content">
                     <i :class="iconClass" /> 
@@ -17,7 +17,7 @@
 
 <script>
 import ConfirmationEventBus from 'primevue/confirmationeventbus';
-import {ConnectedOverlayScrollHandler,DomHandler} from 'primevue/utils';
+import {ConnectedOverlayScrollHandler,DomHandler,ZIndexUtils} from 'primevue/utils';
 import OverlayEventBus from 'primevue/overlayeventbus';
 import Button from 'primevue/button';
 
@@ -65,8 +65,13 @@ export default {
             this.scrollHandler = null;
         }
         this.unbindResizeListener();
+
+        if (this.container) {
+            ZIndexUtils.clear(this.container);
+            this.container = null;
+        }
+
         this.target = null;
-        this.container = null;
         this.confirmation = null;
     },
     methods: {
@@ -84,18 +89,22 @@ export default {
 
             this.visible = false;
         },
-        onEnter() {
+        onEnter(el) {
             this.alignOverlay();
             this.bindOutsideClickListener();
             this.bindScrollListener();
             this.bindResizeListener();
-            this.container.style.zIndex = String(this.baseZIndex + DomHandler.generateZIndex());
+
+            ZIndexUtils.set('overlay', el, this.$primevue.config.zIndex.overlay);
         },
         onLeave() {
             this.unbindOutsideClickListener();
             this.unbindScrollListener();
             this.unbindResizeListener();
         },
+        onAfterLeave(el) {
+            ZIndexUtils.clear(el);
+        },
         alignOverlay() {
             DomHandler.absolutePosition(this.container, this.target);
 
diff --git a/src/components/contextmenu/ContextMenu.vue b/src/components/contextmenu/ContextMenu.vue
index 1eaee9adb..24e57eaed 100755
--- a/src/components/contextmenu/ContextMenu.vue
+++ b/src/components/contextmenu/ContextMenu.vue
@@ -1,6 +1,6 @@
 <template>
     <Teleport :to="appendTo">
-        <transition name="p-contextmenu" @enter="onEnter" @leave="onLeave">
+        <transition name="p-contextmenu" @enter="onEnter" @leave="onLeave" @after-leave="onAfterLeave">
             <div :ref="containerRef" class="p-contextmenu p-component" v-if="visible" v-bind="$attrs">
                 <ContextMenuSub :model="model" :root="true" @leaf-click="onLeafClick" />
             </div>
@@ -9,7 +9,7 @@
 </template>
 
 <script>
-import {DomHandler} from 'primevue/utils';
+import {DomHandler,ZIndexUtils} from 'primevue/utils';
 import ContextMenuSub from './ContextMenuSub.vue';
 
 export default {
@@ -52,6 +52,10 @@ export default {
         this.unbindResizeListener();
         this.unbindOutsideClickListener();
         this.unbindDocumentContextMenuListener();
+
+        if (this.container && this.autoZIndex) {
+            ZIndexUtils.clear(this.container);
+        }
         this.container = null;
     },
     mounted() {
@@ -92,19 +96,24 @@ export default {
         hide() {
             this.visible = false;
         },
-        onEnter() {
+        onEnter(el) {
             this.position();
             this.bindOutsideClickListener();
             this.bindResizeListener();
 
             if (this.autoZIndex) {
-                this.container.style.zIndex = String(this.baseZIndex + DomHandler.generateZIndex());
+                ZIndexUtils.set('menu', el, this.baseZIndex + this.$primevue.config.zIndex.menu);
             }
         },
         onLeave() {
             this.unbindOutsideClickListener();
             this.unbindResizeListener();
         },
+        onAfterLeave(el) {
+            if (this.autoZIndex) {
+                ZIndexUtils.clear(el);
+            }
+        },
         position() {
             let left = this.pageX + 1;
             let top = this.pageY + 1;
diff --git a/src/components/dialog/Dialog.vue b/src/components/dialog/Dialog.vue
index bed289d7b..91f0257d3 100755
--- a/src/components/dialog/Dialog.vue
+++ b/src/components/dialog/Dialog.vue
@@ -29,7 +29,7 @@
 </template>
 
 <script>
-import {UniqueComponentId,DomHandler} from 'primevue/utils';
+import {UniqueComponentId,DomHandler,ZIndexUtils} from 'primevue/utils';
 import Ripple from 'primevue/ripple';
 
 export default {
@@ -95,8 +95,13 @@ export default {
     beforeUnmount() {
         this.unbindDocumentState();
         this.destroyStyle();
-        this.container = null;
+        
         this.mask = null;
+
+        if (this.container && this.autoZIndex) {
+            ZIndexUtils.clear(this.container);
+        }
+        this.container = null;
     },
     mounted() {
         if (this.breakpoints) {
@@ -109,7 +114,7 @@ export default {
         },
         onBeforeEnter(el) {
             if (this.autoZIndex) {
-                el.style.zIndex = String(this.baseZIndex + DomHandler.generateZIndex());
+                ZIndexUtils.set('modal', el, this.baseZIndex + this.$primevue.config.zIndex.modal);
             }
             
             el.setAttribute(this.attributeSelector, '');
@@ -127,7 +132,10 @@ export default {
         onLeave() {
             this.$emit('hide');
         },
-        onAfterLeave() {
+        onAfterLeave(el) {
+            if (this.autoZIndex) {
+                ZIndexUtils.clear(el);
+            }
             this.containerVisible = false;
             this.unbindDocumentState();
         },
diff --git a/src/components/dropdown/Dropdown.vue b/src/components/dropdown/Dropdown.vue
index 4d98a3653..6047cb072 100755
--- a/src/components/dropdown/Dropdown.vue
+++ b/src/components/dropdown/Dropdown.vue
@@ -14,7 +14,7 @@
             <span class="p-dropdown-trigger-icon pi pi-chevron-down"></span>
         </div>
         <Teleport :to="appendTo">
-            <transition name="p-connected-overlay" @enter="onOverlayEnter" @leave="onOverlayLeave">
+            <transition name="p-connected-overlay" @enter="onOverlayEnter" @leave="onOverlayLeave" @after-leave="onOverlayAfterLeave">
                 <div :ref="overlayRef" class="p-dropdown-panel p-component" v-if="overlayVisible" @click="onOverlayClick">
                     <slot name="header" :value="modelValue" :options="visibleOptions"></slot>
                     <div class="p-dropdown-header" v-if="filter">
@@ -58,7 +58,7 @@
 </template>
 
 <script>
-import {ConnectedOverlayScrollHandler,ObjectUtils,DomHandler} from 'primevue/utils';
+import {ConnectedOverlayScrollHandler,ObjectUtils,DomHandler,ZIndexUtils} from 'primevue/utils';
 import OverlayEventBus from 'primevue/overlayeventbus';
 import {FilterService} from 'primevue/api';
 import Ripple from 'primevue/ripple';
@@ -133,8 +133,13 @@ export default {
             this.scrollHandler.destroy();
             this.scrollHandler = null;
         }
+
         this.itemsWrapper = null;
-        this.overlay = null;
+        
+        if (this.overlay) {
+            ZIndexUtils.clear(this.overlay);
+            this.overlay = null;
+        }
     },
     methods: {
         getOptionLabel(option) {
@@ -386,8 +391,8 @@ export default {
         onEditableInput(event) {
             this.$emit('update:modelValue', event.target.value);
         },
-        onOverlayEnter() {
-            this.overlay.style.zIndex = String(DomHandler.generateZIndex());
+        onOverlayEnter(el) {
+            ZIndexUtils.set('overlay', el, this.$primevue.config.zIndex.overlay);
             this.scrollValueInView();
             this.alignOverlay();
             this.bindOutsideClickListener();
@@ -408,6 +413,9 @@ export default {
             this.itemsWrapper = null;
             this.overlay = null;
         },
+        onOverlayAfterLeave(el) {
+            ZIndexUtils.clear(el);
+        },
         alignOverlay() {
             this.overlay.style.minWidth = DomHandler.getOuterWidth(this.$el) + 'px';
             DomHandler.absolutePosition(this.overlay, this.$el);
diff --git a/src/components/galleria/Galleria.vue b/src/components/galleria/Galleria.vue
index 978c19ab6..ac63bf0e1 100755
--- a/src/components/galleria/Galleria.vue
+++ b/src/components/galleria/Galleria.vue
@@ -11,7 +11,7 @@
 
 <script>
 import GalleriaContent from './GalleriaContent.vue';
-import {DomHandler} from 'primevue/utils';
+import {DomHandler,ZIndexUtils} from 'primevue/utils';
 
 export default {
     inheritAttrs: false,
@@ -131,21 +131,25 @@ export default {
             DomHandler.removeClass(document.body, 'p-overflow-hidden');
         }
 
-        this.container = null;
         this.mask = null;
+        if (this.container) {
+            ZIndexUtils.clear(this.container);
+            this.container = null;
+        }
     },
     methods: {
         onBeforeEnter(el) {
-            el.style.zIndex = String(this.baseZIndex + DomHandler.generateZIndex());
+            ZIndexUtils.set('modal', el, this.baseZIndex || this.$primevue.config.zIndex.modal);
         },
-        onEnter() {
-            this.mask.style.zIndex = String(this.baseZIndex + DomHandler.generateZIndex());
+        onEnter(el) {
+            this.mask.style.zIndex = String(parseInt(el.style.zIndex, 10) - 1);
             DomHandler.addClass(document.body, 'p-overflow-hidden');
         },
         onBeforeLeave() {
             DomHandler.addClass(this.mask, 'p-galleria-mask-leave');
         },
-        onAfterLeave() {
+        onAfterLeave(el) {
+            ZIndexUtils.clear(el);
             this.containerVisible = false;
             DomHandler.removeClass(document.body, 'p-overflow-hidden');
         },
diff --git a/src/components/menu/Menu.vue b/src/components/menu/Menu.vue
index 3bb0f5f02..5245f801e 100755
--- a/src/components/menu/Menu.vue
+++ b/src/components/menu/Menu.vue
@@ -1,6 +1,6 @@
 <template>
     <Teleport :to="appendTo" :disabled="!popup">
-        <transition name="p-connected-overlay" @enter="onEnter" @leave="onLeave">
+        <transition name="p-connected-overlay" @enter="onEnter" @leave="onLeave" @after-leave="onAfterLeave">
             <div :ref="containerRef" :class="containerClass" v-if="popup ? overlayVisible : true" v-bind="$attrs" @click="onOverlayClick">
                 <ul class="p-menu-list p-reset" role="menu">
                     <template v-for="(item, i) of model" :key="item.label + i.toString()">
@@ -21,7 +21,7 @@
 </template>
 
 <script>
-import {ConnectedOverlayScrollHandler,DomHandler} from 'primevue/utils';
+import {ConnectedOverlayScrollHandler,DomHandler,ZIndexUtils} from 'primevue/utils';
 import OverlayEventBus from 'primevue/overlayeventbus';
 import Menuitem from './Menuitem.vue';
 
@@ -68,6 +68,10 @@ export default {
             this.scrollHandler = null;
         }
         this.target = null;
+        
+        if (this.container && this.autoZIndex) {
+            ZIndexUtils.clear(this.container);
+        }
         this.container = null;
     },
     methods: {
@@ -101,14 +105,14 @@ export default {
             this.overlayVisible = false;
             this.target = null;
         },
-        onEnter() {
+        onEnter(el) {
             this.alignOverlay();
             this.bindOutsideClickListener();
             this.bindResizeListener();
             this.bindScrollListener();
 
             if (this.autoZIndex) {
-                this.container.style.zIndex = String(this.baseZIndex + DomHandler.generateZIndex());
+                ZIndexUtils.set('menu', el, this.baseZIndex + this.$primevue.config.zIndex.menu);
             }
         },
         onLeave() {
@@ -116,6 +120,11 @@ export default {
             this.unbindResizeListener();
             this.unbindScrollListener();
         },
+        onAfterLeave(el) {
+            if (this.autoZIndex) {
+                ZIndexUtils.clear(el);
+            }
+        },
         alignOverlay() {
             DomHandler.absolutePosition(this.container, this.target);
             this.container.style.minWidth = DomHandler.getOuterWidth(this.target) + 'px';
diff --git a/src/components/menubar/Menubar.vue b/src/components/menubar/Menubar.vue
index 5624a3bca..0fd380409 100755
--- a/src/components/menubar/Menubar.vue
+++ b/src/components/menubar/Menubar.vue
@@ -15,7 +15,7 @@
 
 <script>
 import MenubarSub from './MenubarSub.vue';
-import {DomHandler} from 'primevue/utils';
+import {ZIndexUtils} from 'primevue/utils';
 
 export default {
     props: {
@@ -33,11 +33,21 @@ export default {
     beforeUnmount() {
         this.mobileActive = false;
         this.unbindOutsideClickListener();
+        if (this.$refs.rootmenu && this.$refs.rootmenu.$el) {
+            ZIndexUtils.clear(this.$refs.rootmenu.$el);
+        }
     },
     methods: {
         toggle(event) {
-            this.mobileActive = !this.mobileActive;
-            this.$refs.rootmenu.$el.style.zIndex = String(DomHandler.generateZIndex());
+            if (this.mobileActive) {
+                this.mobileActive = false;
+                ZIndexUtils.clear(this.$refs.rootmenu.$el);
+            }
+            else {
+                this.mobileActive = true;
+                ZIndexUtils.set('menu', this.$refs.rootmenu.$el, this.$primevue.config.zIndex.menu);
+            }
+            
             this.bindOutsideClickListener();
             event.preventDefault();
         },
diff --git a/src/components/multiselect/MultiSelect.vue b/src/components/multiselect/MultiSelect.vue
index 961639cc3..a7ae3b8d4 100755
--- a/src/components/multiselect/MultiSelect.vue
+++ b/src/components/multiselect/MultiSelect.vue
@@ -24,7 +24,7 @@
             <span class="p-multiselect-trigger-icon pi pi-chevron-down"></span>
         </div>
         <Teleport :to="appendTo">
-            <transition name="p-connected-overlay" @enter="onOverlayEnter" @leave="onOverlayLeave">
+            <transition name="p-connected-overlay" @enter="onOverlayEnter" @leave="onOverlayLeave" @after-leave="onOverlayAfterLeave">
                 <div :ref="overlayRef" class="p-multiselect-panel p-component" v-if="overlayVisible" @click="onOverlayClick">
                     <slot name="header" :value="modelValue" :options="visibleOptions"></slot>
                     <div class="p-multiselect-header">
@@ -93,7 +93,7 @@
 </template>
 
 <script>
-import {ConnectedOverlayScrollHandler,ObjectUtils,DomHandler} from 'primevue/utils';
+import {ConnectedOverlayScrollHandler,ObjectUtils,DomHandler,ZIndexUtils} from 'primevue/utils';
 import OverlayEventBus from 'primevue/overlayeventbus';
 import {FilterService} from 'primevue/api';
 import Ripple from 'primevue/ripple';
@@ -166,7 +166,11 @@ export default {
             this.scrollHandler.destroy();
             this.scrollHandler = null;
         }
-        this.overlay = null;
+        
+        if (this.overlay) {
+            ZIndexUtils.clear(this.overlay);
+            this.overlay = null;
+        }
     },
     methods: {
         getOptionLabel(option) {
@@ -340,8 +344,8 @@ export default {
             else
                 return null;
         },
-        onOverlayEnter() {
-            this.overlay.style.zIndex = String(DomHandler.generateZIndex());
+        onOverlayEnter(el) {
+            ZIndexUtils.set('overlay', el, this.$primevue.config.zIndex.overlay);
             this.alignOverlay();
             this.bindOutsideClickListener();
             this.bindScrollListener();
@@ -355,6 +359,9 @@ export default {
             this.$emit('hide');
             this.overlay = null;
         },
+        onOverlayAfterLeave(el) {
+            ZIndexUtils.clear(el);
+        },
         alignOverlay() {
             this.overlay.style.minWidth = DomHandler.getOuterWidth(this.$el) + 'px';
             DomHandler.absolutePosition(this.overlay, this.$el);
diff --git a/src/components/overlaypanel/OverlayPanel.vue b/src/components/overlaypanel/OverlayPanel.vue
index 31dd36734..140b5bc58 100755
--- a/src/components/overlaypanel/OverlayPanel.vue
+++ b/src/components/overlaypanel/OverlayPanel.vue
@@ -1,6 +1,6 @@
 <template>
     <Teleport :to="appendTo">
-        <transition name="p-overlaypanel" @enter="onEnter" @leave="onLeave">
+        <transition name="p-overlaypanel" @enter="onEnter" @leave="onLeave" @after-leave="onAfterLeave">
             <div class="p-overlaypanel p-component" v-if="visible" :ref="containerRef" v-bind="$attrs" @click="onOverlayClick">
                 <div class="p-overlaypanel-content" @click="onContentClick">
                     <slot></slot>
@@ -14,7 +14,7 @@
 </template>
 
 <script>
-import {UniqueComponentId,DomHandler,ConnectedOverlayScrollHandler} from 'primevue/utils';
+import {UniqueComponentId,DomHandler,ConnectedOverlayScrollHandler,ZIndexUtils} from 'primevue/utils';
 import OverlayEventBus from 'primevue/overlayeventbus';
 import Ripple from 'primevue/ripple';
 
@@ -74,6 +74,10 @@ export default {
         this.destroyStyle();
         this.unbindResizeListener();
         this.target = null;
+
+        if (this.container && this.autoZIndex) {
+            ZIndexUtils.clear(this.container);
+        }
         this.container = null;
     },
     mounted() {
@@ -98,7 +102,7 @@ export default {
         onContentClick() {
             this.selfClick = true;
         },
-        onEnter() {
+        onEnter(el) {
             this.container.setAttribute(this.attributeSelector, '');
             this.alignOverlay();
             if (this.dismissable) {
@@ -109,8 +113,9 @@ export default {
             this.bindResizeListener();
 
             if (this.autoZIndex) {
-                this.container.style.zIndex = String(this.baseZIndex + DomHandler.generateZIndex());
+                ZIndexUtils.set('overlay', el, this.baseZIndex + this.$primevue.config.zIndex.overlay);
             }
+
             OverlayEventBus.on('overlay-click', e => {
                 if (this.container.contains(e.target)) {
                     this.selfClick = true;
@@ -123,6 +128,11 @@ export default {
             this.unbindResizeListener();
             OverlayEventBus.off('overlay-click');
         },
+        onAfterLeave(el) {
+            if (this.autoZIndex) {
+                ZIndexUtils.clear(el);
+            }
+        },
         alignOverlay() {
             DomHandler.absolutePosition(this.container, this.target);
 
diff --git a/src/components/password/Password.vue b/src/components/password/Password.vue
index 10fd64a75..f15c80de6 100755
--- a/src/components/password/Password.vue
+++ b/src/components/password/Password.vue
@@ -3,7 +3,7 @@
         <PInputText ref="input" :class="inputFieldClass" :style="inputStyle" :type="inputType" :value="modelValue" @input="onInput" @focus="onFocus" @blur="onBlur" @keyup="onKeyUp" v-bind="$attrs" />
         <i v-if="toggleMask" :class="toggleIconClass" @click="onMaskToggle" />
         <Teleport :to="appendTo">
-            <transition name="p-connected-overlay" @enter="onOverlayEnter" @leave="onOverlayLeave">
+            <transition name="p-connected-overlay" @enter="onOverlayEnter" @leave="onOverlayLeave" @after-leave="onOverlayAfterLeave">
                 <div :ref="overlayRef" class="p-password-panel p-component" v-if="overlayVisible" @click="onOverlayClick">
                     <slot name="header"></slot>
                     <slot name="content">
@@ -20,7 +20,7 @@
 </template>
 
 <script>
-import {ConnectedOverlayScrollHandler,DomHandler} from 'primevue/utils';
+import {ConnectedOverlayScrollHandler,DomHandler,ZIndexUtils} from 'primevue/utils';
 import OverlayEventBus from 'primevue/overlayeventbus';
 import InputText from 'primevue/inputtext';
 
@@ -95,10 +95,15 @@ export default {
             this.scrollHandler.destroy();
             this.scrollHandler = null;
         }
+
+        if (this.overlay) {
+            ZIndexUtils.clear(this.overlay);
+            this.overlay = null;
+        }
     },
     methods: {
-        onOverlayEnter() {
-            this.overlay.style.zIndex = String(DomHandler.generateZIndex());
+        onOverlayEnter(el) {
+            ZIndexUtils.set('overlay', el, this.$primevue.config.zIndex.overlay);
             this.alignOverlay();
             this.bindScrollListener();
             this.bindResizeListener();
@@ -108,6 +113,9 @@ export default {
             this.unbindResizeListener();
             this.overlay = null;
         },
+        onOverlayAfterLeave(el) {
+            ZIndexUtils.clear(el);
+        },
         alignOverlay() {
             this.overlay.style.minWidth = DomHandler.getOuterWidth(this.$refs.input.$el) + 'px';
             DomHandler.absolutePosition(this.overlay, this.$refs.input.$el);
diff --git a/src/components/scrolltop/ScrollTop.vue b/src/components/scrolltop/ScrollTop.vue
index fa2985418..800dcba39 100644
--- a/src/components/scrolltop/ScrollTop.vue
+++ b/src/components/scrolltop/ScrollTop.vue
@@ -1,16 +1,17 @@
 <template>
-    <transition name="p-scrolltop" appear @enter="onEnter">
-        <button :class="containerClass" v-if="visible" @click="onClick" type="button">
+    <transition name="p-scrolltop" appear @enter="onEnter" @after-leave="onAfterLeave">
+        <button :ref="containerRef" :class="containerClass" v-if="visible" @click="onClick" type="button">
             <span :class="iconClass"></span>
         </button>
     </transition>
 </template>
 
 <script>
-import {DomHandler} from 'primevue/utils';
+import {DomHandler,ZIndexUtils} from 'primevue/utils';
 
 export default {
     scrollListener: null,
+    container: null,
     data() {
         return {
             visible: false
@@ -45,6 +46,11 @@ export default {
             this.unbindDocumentScrollListener();
         else if (this.target === 'parent')
             this.unbindParentScrollListener();
+
+        if (this.container) {
+            ZIndexUtils.clear(this.container);
+            this.overlay = null;
+        }
     },
     methods: {
         onClick() {
@@ -86,8 +92,14 @@ export default {
                 this.scrollListener = null;
             }
         },
-        onEnter() {
-            this.$el.style.zIndex = String(DomHandler.generateZIndex());
+        onEnter(el) {
+            ZIndexUtils.set('overlay', el, this.$primevue.config.zIndex.overlay);
+        },
+        onAfterLeave(el) {
+            ZIndexUtils.clear(el);
+        },
+        containerRef(el) {
+            this.container = el;
         }
     },
     computed: {
diff --git a/src/components/sidebar/Sidebar.vue b/src/components/sidebar/Sidebar.vue
index f92f3f907..3827ed79b 100755
--- a/src/components/sidebar/Sidebar.vue
+++ b/src/components/sidebar/Sidebar.vue
@@ -1,7 +1,7 @@
 <template>
     <Teleport to="body">
-        <transition name="p-sidebar" @enter="onEnter" @leave="onLeave" appear>
-            <div :class="containerClass" v-if="visible" ref="container" role="complementary" :aria-modal="modal" v-bind="$attrs">
+        <transition name="p-sidebar" @enter="onEnter" @leave="onLeave" @after-leave="onAfterLeave" appear>
+            <div :class="containerClass" v-if="visible" :ref="containerRef" role="complementary" :aria-modal="modal" v-bind="$attrs">
                 <div class="p-sidebar-content">
                     <button class="p-sidebar-close p-link" @click="hide" :aria-label="ariaCloseLabel" v-if="showCloseIcon" type="button" v-ripple>
                         <span class="p-sidebar-close-icon pi pi-times" />
@@ -14,7 +14,7 @@
 </template>
 
 <script>
-import {DomHandler} from 'primevue/utils';
+import {DomHandler,ZIndexUtils} from 'primevue/utils';
 import Ripple from 'primevue/ripple';
 
 export default {
@@ -56,18 +56,24 @@ export default {
     },
     mask: null,
     maskClickListener: null,
+    container: null,
     beforeUnmount() {
         this.destroyModal();
+
+        if (this.container && this.autoZIndex) {
+            ZIndexUtils.clear(this.container);
+        }
+        this.container = null;
     },
     methods: {
         hide() {
             this.$emit('update:visible', false);
         },
-        onEnter() {
+        onEnter(el) {
             this.$emit('show');
 
             if (this.autoZIndex) {
-                this.$refs.container.style.zIndex = String(this.baseZIndex + DomHandler.generateZIndex());
+                ZIndexUtils.set('modal', el, this.baseZIndex || this.$primevue.config.zIndex.modal);
             }
             this.focus();
             if (this.modal && !this.fullScreen) {
@@ -81,8 +87,13 @@ export default {
                 this.disableModality();
             }
         },
+        onAfterLeave(el) {
+            if (this.autoZIndex) {
+                ZIndexUtils.clear(el);
+            }
+        },
         focus() {
-            let focusable = DomHandler.findSingle(this.$refs.container, 'input,button');
+            let focusable = DomHandler.findSingle(this.container, 'input,button');
             if (focusable) {
                 focusable.focus();
             }
@@ -91,7 +102,7 @@ export default {
             if (!this.mask) {
                 this.mask = document.createElement('div');
                 this.mask.setAttribute('class', 'p-sidebar-mask');
-                this.mask.style.zIndex = String(parseInt(this.$refs.container.style.zIndex, 10) - 1);
+                this.mask.style.zIndex = String(parseInt(this.container.style.zIndex, 10) - 1);
                 if (this.dismissable) {
                     this.bindMaskClickListener();
                 }
@@ -132,6 +143,9 @@ export default {
                 DomHandler.removeClass(document.body, 'p-overflow-hidden');
                 this.mask = null;
             }
+        },
+        containerRef(el) {
+            this.container = el;
         }
     },
     computed: {
diff --git a/src/components/tieredmenu/TieredMenu.vue b/src/components/tieredmenu/TieredMenu.vue
index 0b2e78d55..f921e60b0 100755
--- a/src/components/tieredmenu/TieredMenu.vue
+++ b/src/components/tieredmenu/TieredMenu.vue
@@ -1,6 +1,6 @@
 <template>
     <Teleport :to="appendTo" :disabled="!popup">
-        <transition name="p-connected-overlay" @enter="onEnter" @leave="onLeave">
+        <transition name="p-connected-overlay" @enter="onEnter" @leave="onLeave" @after-leave="onAfterLeave">
             <div :ref="containerRef" :class="containerClass" v-if="popup ? visible : true" v-bind="$attrs" @click="onOverlayClick">
                 <TieredMenuSub :model="model" :root="true" :popup="popup" @leaf-click="onLeafClick"/>
             </div>
@@ -9,7 +9,7 @@
 </template>
 
 <script>
-import {ConnectedOverlayScrollHandler,DomHandler} from 'primevue/utils';
+import {ConnectedOverlayScrollHandler,DomHandler,ZIndexUtils} from 'primevue/utils';
 import OverlayEventBus from 'primevue/overlayeventbus';
 import TieredMenuSub from './TieredMenuSub.vue';
 
@@ -56,6 +56,9 @@ export default {
             this.scrollHandler = null;
         }
         this.target = null;
+        if (this.container && this.autoZIndex) {
+            ZIndexUtils.clear(this.container);
+        }
         this.container = null;
     },
     methods: {
@@ -80,14 +83,14 @@ export default {
         hide() {
             this.visible = false;
         },
-        onEnter() {
+        onEnter(el) {
             this.alignOverlay();
             this.bindOutsideClickListener();
             this.bindResizeListener();
             this.bindScrollListener();
 
             if (this.autoZIndex) {
-                this.container.style.zIndex = String(this.baseZIndex + DomHandler.generateZIndex());
+                ZIndexUtils.set('menu', el, this.baseZIndex + this.$primevue.config.zIndex.menu);
             }
         },
         onLeave() {
@@ -95,6 +98,11 @@ export default {
             this.unbindResizeListener();
             this.unbindScrollListener();
         },
+        onAfterLeave(el) {
+            if (this.autoZIndex) {
+                ZIndexUtils.clear(el);
+            }
+        },
         alignOverlay() {
             DomHandler.absolutePosition(this.container, this.target);
             this.container.style.minWidth = DomHandler.getOuterWidth(this.target) + 'px';
diff --git a/src/components/toast/Toast.vue b/src/components/toast/Toast.vue
index ea41bff77..a5079d98a 100755
--- a/src/components/toast/Toast.vue
+++ b/src/components/toast/Toast.vue
@@ -11,7 +11,7 @@
 <script>
 import ToastEventBus from 'primevue/toasteventbus';
 import ToastMessage from './ToastMessage.vue';
-import {DomHandler} from 'primevue/utils';
+import {ZIndexUtils} from 'primevue/utils';
 
 var messageIdx = 0;
 
@@ -55,10 +55,14 @@ export default {
             this.messages = [];
         });
 
-        this.updateZIndex();
+        if (this.autoZIndex) {
+            ZIndexUtils.set('modal', this.$refs.container, this.baseZIndex || this.$primevue.config.zIndex.modal);
+        }
     },
-    beforeUpdate() {
-        this.updateZIndex();
+    beforeUnmount() {
+        if (this.$refs.container && this.autoZIndex) {
+            ZIndexUtils.clear(this.$refs.container);
+        }
     },
     methods: {
         add(message) {
@@ -78,11 +82,6 @@ export default {
             }
 
             this.messages.splice(index, 1);
-        },
-        updateZIndex() {
-            if (this.autoZIndex) {
-                this.$refs.container.style.zIndex = String(this.baseZIndex + DomHandler.generateZIndex());
-            }
         }
     },
     components: {
diff --git a/src/components/tooltip/Tooltip.js b/src/components/tooltip/Tooltip.js
index adbf4afb3..93154316f 100755
--- a/src/components/tooltip/Tooltip.js
+++ b/src/components/tooltip/Tooltip.js
@@ -1,6 +1,4 @@
-import {UniqueComponentId} from 'primevue/utils';
-import {DomHandler} from 'primevue/utils';
-import {ConnectedOverlayScrollHandler} from 'primevue/utils';
+import {UniqueComponentId,DomHandler,ConnectedOverlayScrollHandler,ZIndexUtils} from 'primevue/utils';
 
 function bindEvents(el) {
     const modifiers = el.$_ptooltipModifiers;
@@ -72,7 +70,6 @@ function show(el) {
     let tooltipElement = create(el);
     align(el);
     DomHandler.fadeIn(tooltipElement, 250);
-    tooltipElement.style.zIndex = ++DomHandler.zindex;
 
     window.addEventListener('resize', function onWindowResize() {
         hide(el);
@@ -80,11 +77,13 @@ function show(el) {
     });
 
     bindScrollListener(el);
+    ZIndexUtils.set('tooltip', tooltipElement, el.$_ptooltipZIndex);
 }
 
 function hide(el) {
     remove(el);
     unbindScrollListener(el);
+    ZIndexUtils.clear(el);
 }
 
 function getTooltipElement(el) {
@@ -245,6 +244,7 @@ const Tooltip = {
         let target = getTarget(el);
         target.$_ptooltipModifiers = options.modifiers;
         target.$_ptooltipValue = options.value;
+        target.$_ptooltipZIndex = options.instance.$primevue && options.instance.$primevue.config && options.instance.$primevue.config.zIndex.tooltip;
         bindEvents(target);
     },
     unmounted(el) {
@@ -256,6 +256,8 @@ const Tooltip = {
             target.$_ptooltipScrollHandler.destroy();
             target.$_ptooltipScrollHandler = null;
         }
+
+        ZIndexUtils.clear(el);
     },
     updated(el, options) {
         let target = getTarget(el);
diff --git a/src/components/treeselect/TreeSelect.vue b/src/components/treeselect/TreeSelect.vue
index 11a85c6e3..f6adf28c4 100644
--- a/src/components/treeselect/TreeSelect.vue
+++ b/src/components/treeselect/TreeSelect.vue
@@ -23,7 +23,7 @@
             <span class="p-treeselect-trigger-icon pi pi-chevron-down"></span>
         </div>
         <Teleport :to="appendTo">
-            <transition name="p-connected-overlay" @enter="onOverlayEnter" @leave="onOverlayLeave">
+            <transition name="p-connected-overlay" @enter="onOverlayEnter" @leave="onOverlayLeave" @after-leave="onOverlayAfterLeave">
                 <div :ref="overlayRef" v-if="overlayVisible" @click="onOverlayClick" :class="['p-treeselect-panel p-component', panelClass]">
                     <slot name="header" :value="modelValue" :options="options"></slot>
                     <div class="p-treeselect-items-wrapper" :style="{'max-height': scrollHeight}">
@@ -43,7 +43,7 @@
 </template>
 
 <script>
-import {ConnectedOverlayScrollHandler,DomHandler} from 'primevue/utils';
+import {ConnectedOverlayScrollHandler,DomHandler,ZIndexUtils} from 'primevue/utils';
 import OverlayEventBus from 'primevue/overlayeventbus';
 import Tree from 'primevue/tree';
 import Ripple from 'primevue/ripple';
@@ -121,7 +121,11 @@ export default {
             this.scrollHandler.destroy();
             this.scrollHandler = null;
         }
-        this.overlay = null;
+        
+        if (this.overlay) {
+            ZIndexUtils.clear(this.overlay);
+            this.overlay = null;
+        }
     },
     mounted() {
         this.updateTreeState();
@@ -204,8 +208,8 @@ export default {
                 break;
             }
         },
-        onOverlayEnter() {
-            this.overlay.style.zIndex = String(DomHandler.generateZIndex());
+        onOverlayEnter(el) {
+            ZIndexUtils.set('overlay', el, this.$primevue.config.zIndex.overlay);
             this.alignOverlay();
             this.bindOutsideClickListener();
             this.bindScrollListener();
@@ -219,6 +223,9 @@ export default {
             this.$emit('hide');
             this.overlay = null;
         },
+        onOverlayAfterLeave(el) {
+            ZIndexUtils.clear(el);
+        },
         alignOverlay() {
             this.overlay.style.minWidth = DomHandler.getOuterWidth(this.$el) + 'px';
             DomHandler.absolutePosition(this.overlay, this.$el);
diff --git a/src/components/utils/DomHandler.js b/src/components/utils/DomHandler.js
index 12988053d..19e663b53 100755
--- a/src/components/utils/DomHandler.js
+++ b/src/components/utils/DomHandler.js
@@ -93,15 +93,6 @@ export default class DomHandler {
         };
     }
 
-    static generateZIndex() {
-        this.zindex = this.zindex||999;
-        return ++this.zindex;
-    }
-
-    static getCurrentZIndex() {
-        return this.zindex;
-    }
-
     static index(element) {
         let children = element.parentNode.childNodes;
         let num = 0;
diff --git a/src/components/utils/Utils.js b/src/components/utils/Utils.js
index 87eb125bd..7fb0c477f 100644
--- a/src/components/utils/Utils.js
+++ b/src/components/utils/Utils.js
@@ -1,7 +1,8 @@
 import ConnectedOverlayScrollHandler from './ConnectedOverlayScrollHandler';
 import DomHandler from './DomHandler';
 import ObjectUtils from './ObjectUtils';
+import ZIndexUtils from './ZIndexUtils';
 import UniqueComponentId from './UniqueComponentId';
 import EventBus from './EventBus';
 
-export {ConnectedOverlayScrollHandler,DomHandler,ObjectUtils,UniqueComponentId,EventBus};
\ No newline at end of file
+export {ConnectedOverlayScrollHandler,DomHandler,ObjectUtils,ZIndexUtils,UniqueComponentId,EventBus};
\ No newline at end of file
diff --git a/src/components/utils/ZIndexUtils.js b/src/components/utils/ZIndexUtils.js
new file mode 100644
index 000000000..5d7ba543d
--- /dev/null
+++ b/src/components/utils/ZIndexUtils.js
@@ -0,0 +1,41 @@
+function handler() {
+    let zIndexes = [];
+
+    const generateZIndex = (key, baseZIndex) => {
+        let lastZIndex = zIndexes.length > 0 ? zIndexes[zIndexes.length - 1] : { key, value: baseZIndex };
+        let newZIndex = lastZIndex.value + (lastZIndex.key === key ? 0 : baseZIndex) + 1;
+
+        zIndexes.push({ key, value: newZIndex });
+        return newZIndex;
+    }
+
+    const revertZIndex = (zIndex) => {
+        zIndexes = zIndexes.filter(obj => obj.value !== zIndex);
+    }
+
+    const getCurrentZIndex = () => {
+        return zIndexes.length > 0 ? zIndexes[zIndexes.length - 1].value : 0;
+    }
+
+    const getZIndex = (el) => {
+        return el ? parseInt(el.style.zIndex, 10) || 0 : 0
+    }
+
+    return {
+        get: getZIndex,
+        set: (key, el, baseZIndex) => {
+            if (el) {
+                el.style.zIndex = String(generateZIndex(key, baseZIndex));
+            }
+        },
+        clear: (el) => {
+            if (el) {
+                revertZIndex(getZIndex(el));
+                el.style.zIndex = '';
+            }
+        },
+        getCurrent: () => getCurrentZIndex()
+    };
+}
+
+export default handler();
\ No newline at end of file
diff --git a/src/views/setup/Setup.vue b/src/views/setup/Setup.vue
index 61ab81f1e..bd811233b 100755
--- a/src/views/setup/Setup.vue
+++ b/src/views/setup/Setup.vue
@@ -220,6 +220,25 @@ app.use(PrimeVue, {ripple: true});
 
 </code></pre>
 
+            <h5>ZIndex Layering</h5>
+            <p>ZIndexes are managed automatically to make sure layering of overlay components work seamlessly when combining multiple components. Still there may be cases where you'd like to configure
+            the configure default values such as a custom layout where header section is fixed. In a case like this, dropdown needs to be displayed below the application header but a modal dialog should be displayed above. PrimeVue configuration
+            offers the <i>zIndex</i> property to customize the default values for components categories. Default values are described below and can be customized when setting up PrimeVue.</p>
+<pre v-code.script><code>
+import {createApp} from 'vue';
+import PrimeVue from 'primevue/config';
+const app = createApp(App);
+
+app.use(PrimeVue, {
+    zIndex: {
+        modal: 1100,        //dialog, sidebar
+        overlay: 1000,      //dropdown, overlaypanel
+        menu: 1000,         //overlay menus
+        tooltip: 1100       //tooltip
+    }
+});
+
+</code></pre>
             <h5>Locale</h5>
             <p>PrimeVue provides a Locale API to support i18n and l7n, visit the <router-link to="/locale">Locale</router-link> documentation for more information.</p>