Character pass through
Update. I found a workaround from this thread: http://lexicalclosures.blogspot.com/2010/10/emacs-resharper-visual-studio-xkeymacs.html which is interesting since it documents a number of subtle issues with visual studio and xkeymacs interactions.
Anyway idea for use with Visual Studio is to use (fset 'some-name "<unused-key>") in the *.xkeymacs file then from the advanced -> original commands tab bind it to the key you really want. Then go ahead and define the command you want to run in Visual Studio to the <unused-key>. I suppose this would work with any program that allows you define your own keybindings...
I'm sorry for my too late response. If you want "C-xC-f" does nothing, you should bind "C-xC-f" with the function "Ignore" on the Advanced tab on the property dialog. If you want further tips, please give me an actual example of what you want to do with XKeymacs.
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I like to bind additional functionality in Visual Studio to Emacs prefixes. For example a significantly nicer find file dialog to say C-x C-f. If I disable that feature in XKeymacs I still can't use that key combination because XKeymacs consumes the C-x and only passes through the C-f. I believe this is incorrect behavior since it should either pass through BOTH characters or neither and you should be able to choose which. Emacs itself would consume both characters if the 2nd character wasn't bound to a command. Perhaps a simple check box to determine behavior, or alternatively a built-in "pass-through" command which I could then bind multiple key combinations to and it would simply re-send the key combinations when received...
Thanks!