I have 3 large monitors and a 46" flat screen, I use different media players (when playing from a file and not XMM) depending on which screen I want the video/movie to open on. This saves time dragging players around etc. It would be very handy if the Play File function/button gave the option of opening with.... and a list of available players ie: whatever you have installed, a "browse to" option to lead to the executables... Just an idea as I am sure many people like myself have large screens in rooms other than the one they are sitting in so they can play movies in a sitting room etc. My KM Player opens on my 46 inch flat screen in another room but if I want to play something on the monitor at my computer I have to actually go to the file and right click open with UM player or one of several others i use.
I am glad you like my idea multiple monitors are getting much more common these days and make using multiple players a good option rather than dragging and dropping them from screen to screen. Perhaps Ale will have time to look into it one day. :-)