Fixes to the Drawing code

Hi team,
While Fixing the Framebuffer Surface class i've stumbled across a few 
problems.
1. Clip rect was basicly always set to the size of the widget beeing 
drawn, this means that each redraw the whole screen is redrawn because 
state's rect is the size of the screen
2. There "was" some code in container which added the area of all childs 
widgets intersecting with the redraw_rect given to the redraw_rect, imo 
this is highly unnecesary because they get redrawn anyway and with the 
clip_rectangle they'll be clipped to only update the part which has changed.
3. The FBdev backend was highly broken *g*

Please comment on these issues, i'd like to get some feedback, my 
changed should be in cvs, together with the preliminary Spreadsheet widget