To clear out old entries (esp. wine) from your "open with" window, delete everything in ~/.local/share/applicationsCory Sadowski adds:
~/.local/share/applications/mimeapps.list is what stores certain file associations, notably the one that controls what application opens when you click a location in the Places bar. Install LXDE and suddenly find that PCManFM has taken over your Places menu? Look in mimeapps.list and introduce that jerk to your delete key.