This is a preparation for using multiple contexts on one drawable to
handle multithreading.

I forgot that when re-enabling register combiners during the state
management rewrite.

winex11.drv: In the case requested glyphs do not present in the font fail gracefully instead of asserting.

Modify the behavior when the messages TBM_SETSEL, TBM_SETSELSTART, and
TBM_SETSELEND are sent and TBS_ENABLESELRANGE is not set.  When the
style TBS_ENABLESELRANGE is not set, Windows observed behavior is to
set the Selection Start and End values to 0, rather than leave them
unchanged.