GDI leak fixed in multiwindow mode, thanks to Kensuke's work

[Earle F. Philhower III]

I've just CVS commited a 1-line patch for the GDI leak I found
last night.  It's actually the same patch Kensuke did a few hours
ago, but it wasn't applied to the MultiWindow files.  [I'm not
complaining, I forgot to apply the off-by-one classname fix to
Kensuke's rootless code, too...]

It seems that we've got a lot of cut-n-pasted code in XWin. :(
If someone has a few spare hours they should see if we can add
a common multiwindow utility function file for things like
generating class names or reloading the g_hiconX.