How to create a modal window which only masks a particular component in ExtJs 4?

I would like to create a modal window which will only mask the center region of my application.

How can I achieve this?

In ExtJs 3 I was able to use the windows renderTo property and render the window to the center region. So that when the window was shown only the center region was masked.

However if I use the renderTo property in ExtJs 4 the whole document.body is masked. And in IE the whole the window is also masked.

Below is the border layout example from the Ext Examples. with a modal window in the center region. ( the whole body gets masked when shown)

  Ext.onReady(function() {
var cw;

Ext.create('Ext.Viewport', {
    layout: {
        type: 'border',
        padding: 5
    },
    defaults: {
        split: true
    },
    items: [{
        region: 'north',
        collapsible: true,
        title: 'North',
        split: true,
        height: 100,
        html: 'north'
    },{
        region: 'west',
        collapsible: true,
        title: 'Starts at width 30%',
        split: true,
        width: '30%',
        html: 'west<br>I am floatable'
    },{
        region: 'center',
        layout: 'border',
        border: false,
        items: [{
            region: 'center',
            html: 'center center',
            title: 'Center',
            items: [cw = Ext.create('Ext.Window', {
                xtype: 'window',
                closable: false,
                minimizable: true,
                title: 'Constrained Window',
                height: 200,
                modal: true, //MODAL WINDOW, MASKS THE WHOLE DOCUMENT BODY?
                width: 400,
                constrain: true,
                html: 'I am in a Contain开发者_如何学Cer',
                itemId: 'center-window',
                minimize: function() {
                    this.floatParent.down('button#toggleCw').toggle();
                }
            })],
            dockedItems: [{
                xtype: 'toolbar',
                dock: 'bottom',
                items: ['Text followed by a spacer',
                    ' ', {
                        itemId: 'toggleCw',
                        text: 'Constrained Window',
                        enableToggle: true,
                        toggleHandler: function() {
                        cw.setVisible(!cw.isVisible());
                    }
                }]
            }]
        },{
            region: 'south',
            height: 100,
            split: true,
            collapsible: true,
            title: 'Splitter above me',
            html: 'center south'
        }]
    },{
        region: 'east',
        collapsible: true,
        floatable: true,
        split: true,
        width: 200,
        title: 'East',
        layout: {
            type: 'vbox',
            padding: 5,
            align: 'stretch'
        },
        items: [{
            xtype: 'textfield',
            fieldLabel: 'Text field'
        }, {
            xtype: 'component',
            html: 'I am floatable'
        }]
    },{
        region: 'south',
        collapsible: true,
        split: true,
        height: 200,
        title: 'South',
        layout: {
            type: 'border',
            padding: 5
        },
        items: [{
            title: 'South Central',
            region: 'center',
            html: 'South Central'
        }, {
            title: 'South Eastern',
            region: 'east',
            flex: 1,
            html: 'South Eastern',
            split: true,
            collapsible: true
        }, {
            title: 'South Western',
            region: 'west',
            flex: 1,
            html: 'South Western<br>I collapse to nothing',
            split: true,
            collapsible: true,
            collapseMode: 'mini'
        }]
    }]
});
});

Two ways...

Via the component's ID:

Ext.getCmp('componentId').getEl().mask()

Or via the element's ID:

Ext.get('elementId').mask()

I'm guessing that the first one is what you'll need. You can just bind it to an event listener on the window...

listeners: {
    'show': function() {
        Ext.getCmp('componentId').getEl().mask();
    },
    'hide': function() {
        Ext.getCmp('componentId').getEl().unmask();
    }
}

EDIT:

As described in the ExtJS 4.0.2 API docs... modal masks everything behind the Window, not just it's parent...

True to make the window modal and mask everything behind it when displayed, false to display it without restricting access to other UI elements (defaults to false).

You can add modal window not to the whole viewport, but to the 'center' region only. In this case only this region will be masked. There are some code:

var window = Ext.create('Ext.window.Window', {
    title: 'Hello',
    height: 200,
    width: 400,
    modal: true
});

this.getViewport().child('[region=center]').add(window);
window.show();

use renderTo ctor param

expample:

dialog = new Ext.ux.AnimateWindow({
    renderTo: App.FeedPanel.el.dom.firstElementChild.firstElementChild,
    modal: true,
    title: "Add Feed Source",
    closable: true,
    resizable: false,
    width: 350,
    items: [form]
});