More Variables:
Variables such as player_shields_text work specifically for the current UI, and are rather useless with anything customizable, as is the case for several other variables. Free a lot of those up, giving us separate ones for current shields, max shields, regen, ABSOLUTE VISIBILITY (because relative is useless to a lot of people), and so much more
The variables already exist, just write some public methods for them!
String Concatenation:
While I don't know how easily the XML interacts with the game engines, please find a way to allow this to happen. My current solution with multiple windows is.... well... impractical and a pain in the ass to implement for more complicated UI.
You won't want to underestimate the creative potential of the player base with a customizable UI.
