mono can be a bitch – the following assembly could not be loaded: System.Windows.Forms

What the hell does this mean?

** (MyProgram.exe:2938): WARNING **: The following assembly referenced from /home/dj/Development/MyProgram/MyProgram.exe could not be loaded:
Assembly:   System.Windows.Forms    (assemblyref_index=1)
Version:    2.0.0.0
Public Key: b77a5c561934e089
The assembly was not found in the Global Assembly Cache, a path listed in the MONO_PATH environment variable, or in the location of the executing assembly (/home/dj/Development/MyProgram/).

** (MyProgram.exe:2938): WARNING **: Could not load file or assembly ‘System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089′ or one of its dependencies.

** (MyProgram.exe:2938): WARNING **: Missing method EnableVisualStyles in assembly /home/dj/Development/MyProgram/MyProgram.exe, type System.Windows.Forms.Application

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 means (or at least it did for me) that you need to:

sudo apt-get install libmono-winforms2.0-cil