I had a look into the webappstore.sqlitefile on my system and it was virtually empty, and the 4-5 lines it did contain were of no significance. Didn't seem to relate specifically to me or my browsing so wonder what sites use this file, and why, cos I obviously don't visit them (or my setup stops it somehow)
all of the FF DOM cookies seem to be in that same webappstore.sqlite file or folder - that maxa app said i had 8 of those cookies but i only had to delete 3 sqlite files or folders over my different firefox profiles - 1 in each profile i guess....