Tab panel - two cards - how to navigate to them
===

I have this code:

    Ext.define('myapp.view.my_view', {
    extend: 'Ext.TabPanel',
    xtype: 'myapp_myview',
    config: {
        fullscreen:true,
	tabBarPosition: 'bottom',
    	items: [
            {
                xtype: 'top_bar'
            },
            {
                xtype: 'title_bar',
            },
    		{
                title: 'TAB 1',
                items: [
                    {
                        xtype: 'myapp_tab1_screen1',
                    },
                    {
                        xtype: 'mayapp_tab1_screen2',
                    },
                ]
    	     }
    	]
    }
    });

I want to have a button in screen1 that slides to screen2, this means that TAB 1 icon is still selected, how do i do this?