A new button is added to the UI so that we can cycle the currently active window when there are more windows to capture. It's like pressing the F11 button but it works on Android too.
* We also make the frame counting consistent: Frame 0 is the frame from
device initialisation to first present, Frame 1 is from first present
to second, and so on after that.
* Dock panels shouldn't have any frame border or anything like that.
* They should have an external margin of 3 pixels at their border,
but then no further margins on the layouts (like sub-controls for
the pipeline state views.
* Toolbars should be Raised & Panel frames. Later we'll replace them
with actual QToolBars to better customise the painting.
baldurk