Tonight I did some work on Wildcat BZR's diff and merge preferences. The preferences dialog now has a list of diff and merge tools that it know about, and can be chosen from a drop down list. Additional diff and merge tools can be supported by specifying the executable and what parameters must be supplied for diffing and merging operations.

At the moment, the following tools are know about, and I will be expanding this list when I have more spare time:

1. SourceGear DiffMerge
2. KDiff3
3. Apple opendiff