Name an icon and cursor theme so MATE lists Diehard4

MATE's Appearance dialog skips any metatheme without IconTheme
(mate-control-center capplets/common/mate-theme-info.c), so Diehard4 was
applied but never listed: it showed as Custom, and switching away lost it.
menta and mate-black are MATE's defaults, so selecting the theme leaves
icons and cursor as they were.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

index.theme

@@ -7,4 +7,6 @@ Encoding=UTF-8
 [X-GNOME-Metatheme]
 GtkTheme=Diehard4
 MetacityTheme=Diehard4
+IconTheme=menta
+CursorTheme=mate-black
 ButtonLayout=:minimize,maximize,close