Improvements for error messages:

Improvements for error messages:
- increase/decrease size on demand and hide progress bar or space information if required
- provide close button

TODO: the code is far from being finished (e. g. no queueing of pending error messages, close button looks fugly, ...), but I decided to commit the changes to prevent getting an inconsistent state in combination with other commits...

svn path=/trunk/playground/utils/dolphin/; revision=628642