Winforms on Mac OSX troubles

Hi,

I'm trying to run a .NET 2.0 application on Mac OSX (10.5.?) and I have many troubles. The first one concerns the interfaces, have a look at this: http://www.lunarpark.be/mono/monoosx.png Such a thing occurs while opening a mdi child window or a dialog window. A refresh() solves the problem but it also occurs while resizing the window, etc...
The second big problem is that mono (and not the .NET application) is always crashing with no reason. Then my question is: is there some limitation to use mono on Mac OSX? Maybe I have a bad configuration... I've been trying the official mono 1.2.6 and the 1.9 preview 3 and 6. But I always have the same problem.

Thanks in advance for your help :)