Revert "cs_themes: Don't mess with the stack switcher's sensitivity."

This reverts commit da63f90, as it
left non-visible buttons sensitive.

79be988 addresses this.

Author: mtwebster

files/usr/share/cinnamon/cinnamon-settings/modules/cs_themes.py

@@ -547,8 +547,10 @@ def set_mode(self, mode, startup=False):
 
         if mode == "simplified":
             switcher_widget.set_opacity(0.0)
+            switcher_widget.set_sensitive(False)
         else:
             switcher_widget.set_opacity(1.0)
+            switcher_widget.set_sensitive(True)
 
         self.sidePage.stack.set_visible_child_full(mode, transition)