Avoid changing the details of a pointer once created.
Properly determine the pointer type for arrays.

Previously the richedit control contents were scrolled directly using
ScrollWindow.  This caused the richedit control to not actually scroll,
but only look like it scrolled, therefore causing plenty of glitches.

That still leaves IWineD3DIndexBuffer, but that code is also mostly similar,
except for the conversion code (which will be unused there).