MainWindow layouting

[Thomas Lübking]

just a check before i start:

the purpose of the signal/timer driven layouting code in MainWindow is to 
preserve a constant aspect between the three docks (media sources, context, 
playlist) - not to actually keep an "up-to-date" copy of the layout in 
permanent memory (the HD), eg. to carry it around segfaults (what should not 
happen in the first place anyway ;-)

right?

Thomas