Applies to Ext JS 4 Preview 1

It looks like ExtJS 3 'margins' config property has become 'margin' in ExtJS4. This is not documented properly.
'margins' can still be used as it seems, but when provided as object, it does not get rendered properly, see testcase below (margin left becomes margin right when rendered, margin top becomes margin bottom when rendered).

Code:
Ext.onReady(function(){


    // ---- Create Viewport with border layout ----------------------
    Ext.create('Ext.Viewport',{
        layout: 'border',
        padding:20,
        defaults: {
                padding: 5,
                frame: true
        },
        items:[
            {
                region: 'north',
                title: 'Panel North',
                html: '<h2>I am North with a left margin of 150 and top and bottom margin of 5</h2>',
                //
                // ExtJS 3 'margins' config property as defined in BoxComponent is now
                // ExtJS 4 'margin' as defined in Ext.Component
                //
                // margin config works when provided as String
                //margin: '5 0 5 150',
                //
                // margin config also works when provided as Object
                //margin: {top:5, right:0, bottom:5,left:150},
                //
                // outdated margins config works NOT correctly in Ext4 preview 1 when provided as Object
                margins: {top:5, right:0, bottom:5,left:150},
                //
                // outdated margins config works correctly when provided as String
                //margins: '5 0 5 150',
                flex: 0.5
            },
            {
                region: 'west',
                title: 'Panel West',
                html: '<h2>I am West</h2>',
                flex: 0.75
            },
            {
                region: 'center',
                title: 'Panel Center',
                html: '<h2>I am Center</h2>',
                margins: '0 5 0 5'
            },
            {
                region: 'east',
                title: 'Panel East',
                html: '<h2>I am East</h2>',
                flex: 0.75
            }
        ]
    });
// END of onReady    
});