bugs and setbacks

general:
- when a messagebox is active, redraw events are not processed, so resizing
  (for example) is messed up.

picross:
- investigate why solver is slow in the presence of yellow on R0806

masyu:
- solver bugs on R0006 if certain other levels (like C141) are solved first

nurikabe:
- solver can't solve 001 after playing for a while (reentrancy?)

slitherlink
- R294 not solved if attempted first, but solved if R293 is done before
