FXRuby & Excel windows

I have a ruby app on Windows, with an FXRuby UI that opens up Excel
using Win32OLE. The Excel window obscures the UI at one point. How
can I programmatically send the Excel window to the back and/or bring
the FXRuby UI to the front. I know I can just not display the the
Excel window at all, but I’d like to leave it open, just behind the
UI, as if the user clicked on the ruby app’s tray icon (which they can
always do manually, if necessary).

Thanks. --David.

PS: Excuse the (manual) cross-posting – forgot about this forum.