And no, the "Remember File" feature is not adequate, as I'll demonstrate.
The feature request is this: DiffMerge should keep a running memory of recently opened files. When files are opened with DiffMerge, the text field where you enter the second file should also be a combobox. You can select a file/directory manually as usual, or select a file/directory from a list of recently comparisons.
1. You can only remember five files. If you use DiffMerge regularly to compare multiple files and source trees, this limitation seriously hampers your workflow. I don't think this needs to be explained. Comparing changes between around fifteen files/directories in a day is usually enough to make me aware of the limit's inadequacy.
2. "Remember File" requires you to be somewhat psychic to get a benefit from it. For example, say I want to compare file apples.cpp and file oranges.cpp, but both live in different trees in my projects folder. I know I compared bananas.cpp to apples.cpp last night, so I know where to look, but I didn't know I would need easy access to have easy apples.cpp in the future so I didn't Remember it. If DiffMerge remembered this for me, I wouldn't need to try to predict the future.
3. "Remember File" still involves needless browsing. Regardless of how I open DiffMerge, my workflow is going to involve browsing to both apples.cpp and oranges.cpp if I want to compare just those two files. If DiffMerge kept a running memory of files I could access, my speed in comparing the two files would double.
4. "Remember File" only works in the context menu. You can't access the information from inside the program itself.
I've only used it on Windows, so if this isn't true for other OSes I'm not aware of it. It seems pretty clear to me that remembering a list of recent files (I would say minimum 30) would add a lot of improvement to the workflow. As far as the context menu goes, "Remember File" should be changed to "Add File to Quicklist", or "Favorites," or whatever you want to call it, which would be placed on top of the recent file list, separated from the recent files by a bar. This would preserve the existing functionality (which does have its uses, such as when you're comparing a tiny portion of a well-known area or need to remember a folder tree you don't access often) while giving you the added benefit of having access to the recent list for comparisons.
Anyway, thank you for releasing DiffMerge. It's become my favorite diff tool in the year or so that I've used it, and my only pain point is the one listed above.
I'll log bug/feature reports on each of these.
The downside of a feature such as this, is that if it's not easy to work with and descriptive, a developer could end up comparing the "wrong" files, thinking he was comparing the "right" files. End result could be lost code or at least a fist fight between developers (just kidding.. maybe).. Just a point to consider..