cursor glitch in at least some HE games which first set a cursor palette, and
then disable it. (The disabled palette would be re-enabled after dismissing the
GUI.)
svn-id: r23081
cursor palette is disabled.
Also, when replacing a cursor palette, try to re-use the old palette buffer, as
a minor optimization. (Not that these functions should need any optimization,
but it's simple and shouldn't hurt.)
svn-id: r22554