Fix the keyboard focus

[GoogleCodeExporter]

Keyboard focus doesn't really work. Currently, in most backends, some component 
gets the keyboard focus, without any rational reason. Currently, this doesn't 
matter since we have no component which depends on the keyboard for it's 
functionallity (Text-Entries are planned for release 2.0), so the user can just 
add the same keyboard listener to all the components. This is not convinient, 
but it works.

Things that focus should support:
1. Always pass to the next focusable component after 'Tab' was pressed
2. The (mouse) clicked component always receives the focus
3. Detect who has the focus also not through a keyboard event

Original issue reported on code.google.com by Lightnin...@gmail.com on 12 Oct 2011 at 11:57