Thanks Sheeo, I haven't really had the chance to open the client for a few days but I'll test with/without hotbuildex and leave logs when I can, probably tonight.
Edit: Deactivated all UI mods, still not getting a functioning close button out of the F1 menu. Logs attached.
Edit 2: There's a thread over in the mod forum with people looking for a mod with hotbuildex functionality.
viewtopic.php?f=41&t=5817#p107197 Will you still debug hotbuildex? Pretty please!