@Matt - I tried to create an External Program under Items to Show in Theater View options. The command was Windows command interpreter, C:\Windows\System32\cmd.exe. Two cmd.exe process are created, and they never go away. Furthermore, no command window appears, regardless of the option to Hide MC while program is running.
MC will launch mspaint.exe just fine. Is this a problem with MC in Theater View working with old-style command shell programs?
(btw. the idea here was to use command shell's copy program with MC passing [filename], allowing the OP's users to select a Copy command from Theater View to copy the given file(s) to the Desktop or some pre-defined folder.)