Resolve window xid when widget is realized
Resolve window xid when widget is realized

A window xid can be used, for example, to draw a GStreamer output to a
widget.

For more details on window handles on Windows, see [here][1].

[1]: http://stackoverflow.com/questions/9259731/getting-gtk-gdk-window-handle-on-windows

wheeler-microfluidics/microdrop