This has been a problem with the Titanium Skin since it was first rolled out and made the default skin. The creator has not yet fixed it. You can switch to the 'Basic' skin and the buttons are correct.
I'll give this a try too. That way I have a baseline of the intended way the orbiter screens are supposed to work.
I'm kind of a noob with LinuxMCE at this point, but am very impressed with it so far. I've done linux development in the past and am happy to contribute back to this project where ever it makes sense.
I checked svn after posting and it looks like there is a ticket associated with this: http://svn.linuxmce.org/trac.cgi/ticket/306.