One other filter that would be really useful (but this is probably super hard to do) is in the Project Tree. When opening old projects sometimes it's hard to remember where a particular Variable was used for example and digging through the xml can be a bit impractical, so if there were a filter field on top of the Project Tree where one could drop say a name of the variable and then ZGE would highlight (or something) all the components that use it... Same with finding where a component is used. I usually use the trick of giving a component a wrong name and then attempting to run the project (so the IDE throws me to a ZExpression referencing it) but that is a bit hacky (and calling for trouble

Anyway just an idea, not sure anybody else other than me needs such gadgets...
Edit: I didn't know this at the time of writing the original post but Game Maker has this feature (added relatively recently I guess). Here is what it looks like: Personally I prefer how this feature is implemented in some other programs, for example the Preferences window in Directory Opus has it implemented really well but this one looks good too.