Something that has been really bothering me is not being able to have separate windows in VS2013, one showing my XAML markup and the other showing the actual visual representation of the control or page. Yes, you can split the view, but if like me you run with multiple monitors, you really want one on each screen. Thankfully I have stumbled over a solution!
Open you XAML file by double clicking on it. Now, in the Solution Explorer, right click on the same XAML file and select ‘Open With.’
In the dialog choose the ‘Source Code (Text) Editor’ option and click ‘OK’
A new window in tab, will appear with the XAML markup.
You now have two opened instances of the same file, one with the markup and one with the designer. Feel free to rip those tabs free and throw them where you need them!