Add the UI to preferences for Haskell tools that are not the compiler itself.
Move the brace matcher to the same directory as the commenter.
Move the color settings page o the same directory as the  tools settings.
Separate the execution machinery from the platform dependent parts.
Add a version detection box in the Haskell tools dialogue.
Implement persistency for cabal configuration.
Simplify suggestHomePathForUNIX().
Use --numeric-version to find out the version of GHC.
Add a CompilerConfigurable dialogue.
Group all graphical widgets in one part of plugin.xml.
Fix a string literal bug involving backslashes.