Should be simple enough to implement, but if the source code for Filter Export was available somewhere it might save me a little work and would help me make my feature more consistent with the one that the users are already used to.
Is the source code for Fog Creek plug-ins available somewhere, specifically the Filter export plug-in?
The source code for all of the Fog Creek plugins is shipped with the version of FogBugz you run on your own server. The source files are located in [installation path to FogBugz]/Plugins/examples.
Of course, if you're using FogBugz On Demand, you can't get at such a directory. Just email us at firstname.lastname@example.org and we can email you a copy of the source. Keep in mind that the Filter Export plugin is written in Wasabi, and so reusing its source might require some translation work. :)