Failed to maintain 100% width & height of structure in extjs

Answer 1

It looks like what you really want is a BorderLayout? Also, when you are using Ext layouts, do not use autoHeight -- that means "let the browser determine the height based on content" -- not what you want. Also, there is no need to override initComponent just to supply default configs. Try this instead (not tested):

EditorUi = Ext.extend(Ext.Viewport, {
    layout: 'border',
    items: [{
        xtype: 'panel',
        region: 'north',
        height: 100,                
        title: 'Heading',
    },{
        xtype: 'panel',
        title: 'Navigation',
        collapsible: true,
        region:'west',
        width:200,
        split:'true',
        margins:'3 0 3 3',
        cmargins:'3 3 3 3'
    },{
        xtype: 'panel',
        title: 'container',
        region:'center',
        margins:'3 0 3 3',
        cmargins:'3 3 3 3'
    }];
});

Ext.onReady(function(){
    new EditorUi();
});