IIRC I restricted myself to the generic DLLs of e.g. "I also marked some of the supporting DLLs to load high, namely icudt.dll, icuin.dll, icuuc.dll, hunspell10.dll, libvpx4.dll as they used the most and seemed safe". Seemed safe was good enough for me.
Sometimes I wished I had recorded a list of DLLs required by which app, which would come down to such an utility indeed. A "PM DLL"-ish database for all *.DLL and *.EXE files newer than a specific date. So you can start marking files more safely (used by Mozilla only) or delete files which no longer are required (without e.g. keeping RPM data files in mind).
Recording which DLL files were installed for what reason is easier with a clean eCS boot drive policy, but those records would be based on a random install order of apps and missing DLLs. I know HUNSPEL0.DLL was a new requirement of Mozilla to me, but since that moment it's an assumption that no other app requires this installed, marked DLL. Hmm, compiling a full database wouldn't be that hard. Move DLLs, start the limited number of qualifying apps, restore and record missing DLLs per qualifying app. But then the problem is that I don't install all apps, so such a time-consuming database would only "work for me". Nevertheless it may be easier than writing an illusive utility.
