It's all about where the include is! *smacks self*
When I was first playing with this I had the include up in the top of the file where the button was. I was having trouble that it wouldn't recognize the buttonstyles...I got the black box that dc_roenfanz was describing. After seeing what he/she did to get it working (move the include into the inventory.xml) file, I tried moving it back up to the top of the market.xml file but before the opening page. This *does* work.
It also has the benefit of keeping the number of modded files down. I was trying to stay away from modifying too high up in the heirarchy if I didn't absolutely need to.
I'm still having that flakey side issue where the title and close button don't show if they frame setting is used. I'll see if I can figure that out. Perhaps that has to do with include placement as well since the buttons are between those controls and the frame/backdrop controls.
Thanks dc_roenfanz and Kosmos for lookin at this. At least I'm back on track for the show stopper one.