hmm i ve just read quickly the theming doc, i m not an expert lol
"The mix looks a bit small and the list selection background is cutoff (should go under the the left part)"
i never see the real layout... but i just saw your original screenshoot in the first post, i ve a base for play with, i ll made a best portage.
"Which ratio have you download for your first try?"
not sure of your question lol, i ll try to answer that : your 720p theme (?)
or that: <resolution>1280 1024</resolution>
or that: i ve use the "1b-standard with other mixes" as base and duplicate (by security) [common/common_description/common_info]_1280_1024.xml for isolate my tests
"Problem is adding a ratio is a huge work behind the scene, not to make it works but each time a new game theme is added this is a pain. So i have no plan for now adding it."
yeah, i saw all the directories, not sure to understand actually the complete structure and heritage but yeah a huge work!
A layout editor with drag n drop can be a solution... but, you know that, time is time ...
i ll polish the 5/4 and submit you the changes if you want