Panel with borderLayout fill it's parent body

[tah_206207]

I want to add panel to one of tabs of tabPanel, I use border layout for panel but when i add panel to tab it can't fill it's parent body.
panel code:

var viewport = Ext.create('Ext.panel.Panel', {    layout: {
    type: 'border',
    padding: 5
    },
defaults: {
    split: true,
    anchor:'100%'
    },
id:'viewPort',
width:1200,
height:750,
items: [{
    region: 'west',
    collapsible: true,
    title: 'Starts at width 30%',
    split: true,
    width: '17%',
    minWidth: 100,
    minHeight: 140,
    layout:{
    type:'vbox',
    align:'stretch'
    },
items: [show,treePanel,propGrid]
},tabs]
});

tab code that is parent of panel and when user click on it panel loaded to it dynamically:

var mainTabs = Ext.create('Ext.tab.Panel', {    layout: 'anchor',
    id:'mtabs',
    defaults: {
    split: true,
    anchor: '100%'
    },
items: [{
    title: 'Layout Window',
    closeAction: 'hide',
    layout: {
    type: 'border',
    padding: 5
    },
//anchor: '100%',
width:600,
height:600,
listeners: {
    activate:function (tab) {


    }
},
items: [{
    region: 'west',
    collapsible: true,
    title: 'Starts at width 30%',
    split: true,
    width: '17%',
    minWidth: 100,
    minHeight: 140,
    layout:'vbox',
    items: [historyTreePanel,propGrid]
    },tabs]
},{
    title: 'History',
    //xtype:'panel',
    /*width:2000,
    height:1024,*/
    html: 'Please Wait...',
    id:'history-tab',
    layout:'fit',
    layout: 'hbox',
     default: {
     anchor:'100%'
     },
//iconCls: 'favorites',
//cls: 'card1',
listeners: {
    activate:function (tab) {
    if(!flag){
    flag = true;
        $.getScript("/FleetManagement/js/history/fleethistory.js", function(data, textStatus, jqxhr) {
            var historyTab = Ext.getCmp('history-tab');
            historyTab.add(viewport);
            historyTab.doLayout();
        });
}
}
}
}],
renderTo : Ext.getBody()
});
});

in the above code tab with id:'history-tab' is my mentioned tab.How can i fix this problem?
Untitled.jpg

[mitchellsimoens]

I'm seeing a few things wrong.

I'm assuming the mainTabs tab panel is the tabs variable in the viewport? If it is then the mainTabs should not have renderTo config.

Also you shouldn't change the layout of a tab panel.