    /**
     * @class Ext.ZIndexManager
     * <p>A class that manages a group of {@link Ext.Component#floating} Components and provides z-order management,
     * and Component activation behavior, including masking below the active (topmost) Component.</p>
     * <p>{@link Ext.Component#floating Floating} Components which are rendered directly into the document (Such as {@link Ext.window.Window Window}s which are
     * {@link Ext.Component#show show}n are managed by a {@link Ext.WindowManager global instance}.</p>
     * <p>{@link Ext.Component#floating Floating} Components which are descendants of {@link Ext.Component#floating floating} <i>Containers</i>
     * (For example a {Ext.view.BoundList BoundList} within an {@link Ext.window.Window Window}, or a {@link Ext.menu.Menu Menu}),
     * are managed by a ZIndexManager owned by that floating Container. So ComboBox dropdowns within Windows will have managed z-indices
     * guaranteed to be correct, relative to the Window.</p>
     * @constructor
     */
    Ext.define('Ext.ZIndexManager', {

        alternateClassName: 'Ext.WindowGroup',

        statics: {
            zBase : 9000
        },

        constructor: function(container) {
            var me = this;

            me.list = {};
            me.zIndexStack = [];
            me.front = null;

            if (container) {

                // This is the ZIndexManager for an Ext.container.Container, base its zseed on the zIndex of the Container's element
                if (container.isContainer) {
                    container.on('resize', me._onContainerResize, me);
                    me.zseed = Ext.Number.from(container.getEl().getStyle('zIndex'), me.getNextZSeed());
                    // The containing element we will be dealing with (eg masking) is the content target
                    me.targetEl = container.getTargetEl();
                    me.container = container;
                }
                // This is the ZIndexManager for a DOM element
                else {
                    Ext.EventManager.onWindowResize(me._onContainerResize, me);
                    me.zseed = me.getNextZSeed();
                    me.targetEl = Ext.get(container);
                }
            }
            // No container passed means we are the global WindowManager. Our target is the doc body.
            // DOM must be ready to collect that ref.
            else {
                Ext.EventManager.onWindowResize(me._onContainerResize, me);
                me.zseed = me.getNextZSeed();
                Ext.onDocumentReady(function() {
                    me.targetEl = Ext.getBody();
                });
            }
        },

        getNextZSeed: function() {
            return (Ext.ZIndexManager.zBase += 10000);
        },

        setBase: function(baseZIndex) {
            this.zseed = baseZIndex;
            return this.assignZIndices();
        },

        // private
        assignZIndices: function() {
            var a = this.zIndexStack,
                len = a.length,
                i = 0,
                zIndex = this.zseed,
                comp;

            for (; i < len; i++) {
                comp = a[i];
                if (comp && !comp.hidden) {

                    // Setting the zIndex of a Component returns the topmost zIndex consumed by
                    // that Component.
                    // If it's just a plain floating Component such as a BoundList, then the
                    // return value is the passed value plus 10, ready for the next item.
                    // If a floating *Container* has its zIndex set, it re-orders its managed
                    // floating children, starting from that new base, and returns a value 10000 above
                    // the highest zIndex which it allocates.
                    zIndex = comp.setZIndex(zIndex);
                }
            }
            this._activateLast();
            return zIndex;
        },

        // private
        _setActiveChild: function(comp) {
            if (comp != this.front) {

                if (this.front) {
                    this.front.setActive(false, comp);
                }
                this.front = comp;
                if (comp) {
                    comp.setActive(true);
                    if (comp.modal) {
                        this._showModalMask(comp.el.getStyle('zIndex') - 4);
                    }
                }
            }
        },

        // private
        _activateLast: function(justHidden) {
            var comp,
                lastActivated = false,
                i;

            // Go down through the z-index stack.
            // Activate the next visible one down.
            // Keep going down to find the next visible modal one to shift the modal mask down under
            for (i = this.zIndexStack.length-1; i >= 0; --i) {
                comp = this.zIndexStack[i];
                if (!comp.hidden) {
                    if (!lastActivated) {
                        this._setActiveChild(comp);
                        lastActivated = true;
                    }

                    // Move any modal mask down to just under the next modal floater down the stack
                    if (comp.modal) {
                        this._showModalMask(comp.el.getStyle('zIndex') - 4);
                        return;
                    }
                }
            }

            // none to activate, so there must be no modal mask.
            // And clear the currently active property
            this._hideModalMask();
            if (!lastActivated) {
                this._setActiveChild(null);
            }
        },

        _showModalMask: function(zIndex) {
            if (!this.mask) {
                this.mask = this.targetEl.createChild({
                    cls: Ext.baseCSSPrefix + 'mask'
                });
                this.mask.setVisibilityMode(Ext.core.Element.DISPLAY);
                this.mask.on('click', this._onMaskClick, this);
            }
            Ext.getBody().addCls(Ext.baseCSSPrefix + 'body-masked');
            this.mask.setSize(this.targetEl.getViewSize(true));
            this.mask.setStyle('zIndex', zIndex);
            this.mask.show();
        },

        _hideModalMask: function() {
            if (this.mask) {
                Ext.getBody().removeCls(Ext.baseCSSPrefix + 'body-masked');
                this.mask.hide();
            }
        },

        _onMaskClick: function() {
            if (this.front) {
                this.front.focus();
            }
        },

        _onContainerResize: function() {
            if (this.mask && this.mask.isVisible()) {
                this.mask.setSize(this.targetEl.getViewSize(true));
            }
        },

        /**
         * <p>Registers a floating {@link Ext.Component} with this ZIndexManager. This should not
         * need to be called under normal circumstances. Floating Components (such as Windows, BoundLists and Menus) are automatically registered
         * with a {@link Ext.Component#zIndexManager zIndexManager} at render time.</p>
         * <p>Where this may be useful is moving Windows between two ZIndexManagers. For example,
         * to bring the Ext.MessageBox dialog under the same manager as the Desktop's
         * ZIndexManager in the desktop sample app:</p><code><pre>
    MyDesktop.getDesktop().getManager().register(Ext.MessageBox);
    </pre></code>
         * @param {Component} comp The Component to register.
         */
        register : function(comp) {
            if (comp.zIndexManager) {
                comp.zIndexManager.unregister(comp);
            }
            comp.zIndexManager = this;

            this.list[comp.id] = comp;
            this.zIndexStack.push(comp);
            comp.on('hide', this._activateLast, this);
        },

        /**
         * <p>Unregisters a {@link Ext.Component} from this ZIndexManager. This should not
         * need to be called. Components are automatically unregistered upon destruction.
         * See {@link #register}.</p>
         * @param {Component} comp The Component to unregister.
         */
        unregister : function(comp) {
            delete comp.zIndexManager;
            if (this.list && this.list[comp.id]) {
                delete this.list[comp.id];
                comp.un('hide', this._activateLast);
                Ext.Array.remove(this.zIndexStack, comp);

                // Destruction requires that the topmost visible floater be activated. Same as hiding.
                this._activateLast(comp);
            }
        },

        /**
         * Gets a registered Component by id.
         * @param {String/Object} id The id of the Component or a {@link Ext.Component} instance
         * @return {Ext.Component}
         */
        get : function(id) {
            return typeof id == "object" ? id : this.list[id];
        },

       /**
         * Brings the specified Component to the front of any other active Components in this ZIndexManager.
         * @param {String/Object} comp The id of the Component or a {@link Ext.Component} instance
         * @return {Boolean} True if the dialog was brought to the front, else false
         * if it was already in front
         */
        bringToFront : function(comp) {
            comp = this.get(comp);
            if (comp != this.front) {
                Ext.Array.remove(this.zIndexStack, comp);
                this.zIndexStack.push(comp);
                this.assignZIndices();
                return true;
            }
            if (comp.modal) {
                Ext.getBody().addCls(Ext.baseCSSPrefix + 'body-masked');
                this.mask.setSize(Ext.core.Element.getViewWidth(true), Ext.core.Element.getViewHeight(true));
                this.mask.show();
            }
            return false;
        },

        /**
         * Sends the specified Component to the back of other active Components in this ZIndexManager.
         * @param {String/Object} comp The id of the Component or a {@link Ext.Component} instance
         * @return {Ext.Component} The Component
         */
        sendToBack : function(comp) {
            comp = this.get(comp);
            Ext.Array.remove(this.zIndexStack, comp);
            this.zIndexStack.unshift(comp);
            this.assignZIndices();
            return comp;
        },

        /**
         * Hides all Components managed by this ZIndexManager.
         */
        hideAll : function() {
            for (var id in this.list) {
                if (this.list[id].isComponent && this.list[id].isVisible()) {
                    this.list[id].hide();
                }
            }
        },

        /**
         * @private
         * Temporarily hides all currently visible managed Components. This is for when
         * dragging a Window which may manage a set of floating descendants in its ZIndexManager;
         * they should all be hidden just for the duration of the drag.
         */
        hide: function() {
            var i = 0,
                ln = this.zIndexStack.length,
                comp;

            this.tempHidden = [];
            for (; i < ln; i++) {
                comp = this.zIndexStack[i];
                if (comp.isVisible()) {
                    this.tempHidden.push(comp);
                    comp.hide();
                }
            }
        },

        /**
         * @private
         * Restores temporarily hidden managed Components to visibility.
         */
        show: function() {
            var i = 0,
                ln = this.tempHidden.length,
                comp,
                x,
                y;

            for (; i < ln; i++) {
                comp = this.tempHidden[i];
                x = comp.x;
                y = comp.y;
                comp.show();
                comp.setPosition(x, y);
            }
            delete this.tempHidden;
        },

        /**
         * Gets the currently-active Component in this ZIndexManager.
         * @return {Ext.Component} The active Component
         */
        getActive : function() {
            return this.front;
        },

        /**
         * Returns zero or more Components in this ZIndexManager using the custom search function passed to this method.
         * The function should accept a single {@link Ext.Component} reference as its only argument and should
         * return true if the Component matches the search criteria, otherwise it should return false.
         * @param {Function} fn The search function
         * @param {Object} scope (optional) The scope (<code>this</code> reference) in which the function is executed. Defaults to the Component being tested.
         * that gets passed to the function if not specified)
         * @return {Array} An array of zero or more matching windows
         */
        getBy : function(fn, scope) {
            var r = [],
                i = 0,
                len = this.zIndexStack.length,
                comp;

            for (; i < len; i++) {
                comp = this.zIndexStack[i];
                if (fn.call(scope||comp, comp) !== false) {
                    r.push(comp);
                }
            }
            return r;
        },

        /**
         * Executes the specified function once for every Component in this ZIndexManager, passing each
         * Component as the only parameter. Returning false from the function will stop the iteration.
         * @param {Function} fn The function to execute for each item
         * @param {Object} scope (optional) The scope (<code>this</code> reference) in which the function is executed. Defaults to the current Component in the iteration.
         */
        each : function(fn, scope) {
            var comp;
            for (var id in this.list) {
                comp = this.list[id];
                if (comp.isComponent && fn.call(scope || comp, comp) === false) {
                    return;
                }
            }
        },

        /**
         * Executes the specified function once for every Component in this ZIndexManager, passing each
         * Component as the only parameter. Returning false from the function will stop the iteration.
         * The components are passed to the function starting at the bottom and proceeding to the top.
         * @param {Function} fn The function to execute for each item
         * @param {Object} scope (optional) The scope (<code>this</code> reference) in which the function
         * is executed. Defaults to the current Component in the iteration.
         */
        eachBottomUp: function (fn, scope) {
            var comp,
                stack = this.zIndexStack,
                i, n;

            for (i = 0, n = stack.length ; i < n; i++) {
                comp = stack[i];
                if (comp.isComponent && fn.call(scope || comp, comp) === false) {
                    return;
                }
            }
        },

        /**
         * Executes the specified function once for every Component in this ZIndexManager, passing each
         * Component as the only parameter. Returning false from the function will stop the iteration.
         * The components are passed to the function starting at the top and proceeding to the bottom.
         * @param {Function} fn The function to execute for each item
         * @param {Object} scope (optional) The scope (<code>this</code> reference) in which the function
         * is executed. Defaults to the current Component in the iteration.
         */
        eachTopDown: function (fn, scope) {
            var comp,
                stack = this.zIndexStack,
                i;

            for (i = stack.length ; i-- > 0; ) {
                comp = stack[i];
                if (comp.isComponent && fn.call(scope || comp, comp) === false) {
                    return;
                }
            }
        },

        destroy: function() {
            delete this.zIndexStack;
            delete this.list;
            delete this.container;
            delete this.targetEl;
        }
    }, function() {
        /**
         * @class Ext.WindowManager
         * @extends Ext.ZIndexManager
         * <p>The default global floating Component group that is available automatically.</p>
         * <p>This manages instances of floating Components which were rendered programatically without
         * being added to a {@link Ext.container.Container Container}, and for floating Components which were added into non-floating Containers.</p>
         * <p><i>Floating</i> Containers create their own instance of ZIndexManager, and floating Components added at any depth below
         * there are managed by that ZIndexManager.</p>
         * @singleton
         */
        Ext.WindowManager = Ext.WindowMgr = new this();
    });