When first running XSD Diagram on Ubuntu (12.04.5) it raised an unhandled exception:
Unhandled Exception: System.IO.FileNotFoundException: Could not load file or assembly 'System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' or one of its dependencies.
File name: 'System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'
[ERROR] FATAL UNHANDLED EXCEPTION: System.IO.FileNotFoundException: Could not load file or assembly 'System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' or one of its dependencies.
File name: 'System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'
It might also be helpful to catch that exception and explain to the user what's the problem is.
libgluezilla not found. To have webbrowser support, you need libgluezilla installed