Create buttons for titlebar with proper sizes
Create buttons for titlebar with proper sizes

Instead of creating the titlebar buttons with a size of 10x10 pixels
and rely on resizing later on we now pick the correct dimensions
right on.

This fixes also bug #1125 ("Detaching a window from a tab-group renders
app-icon to 1/2"); the problem also occurred on restart.

I took the chance to refactor a little bit.

naimdjon/fluxbox,olivergondza/fluxbox,Arkq/fluxbox,lukoko/fluxbox,naimdjon/fluxbox,olivergondza/fluxbox,olivergondza/fluxbox,naimdjon/fluxbox,Arkq/fluxbox,Arkq/fluxbox,luebking/fluxbox,naimdjon/fluxbox,luebking/fluxbox,lukoko/fluxbox,lukoko/fluxbox,naimdjon/fluxbox,lukoko/fluxbox,luebking/fluxbox,Arkq/fluxbox,luebking/fluxbox,olivergondza/fluxbox,olivergondza/fluxbox,Arkq/fluxbox,luebking/fluxbox,lukoko/fluxbox