I have noticed that pressing and holding the left mouse button on a RICHEDIT control puts EVERYTHING in the application on hold. Messages just don't go through. The breakpoint set in the application's PreTranslateMessage() (I am using MFC) is never hit until you release the button.
I would like to do some custom processing while the left mouse button is held down. I can't figure out how to overcome that "feature" of the RICHEDIT control.