[Azoz]

It's possible to copy and paste multiple objects through uibuilder. While you cannot select multiple items from the object list by any means, if you select multiple objects in the view window by using shift+click, you can copy by pressing ctrl-c. Now that the selection is in the clipboard you can paste all of those objects together with ctrl-v or edit->paste.

Also, it's not particularly hidden but I've found I like to change the default settings for new objects view->default properties then select your object and add a new property and default value for it. I find it really useful for text since it has no default font or shadow style normally.

Double click everything. Like the color selector and the truefalse toggle mentioned here, I also discovered that double clicking a dynamic data that is set to /gamedata.self.name (you must double click the text that says "dynamicdata" otherwise you will be editing the value) it will move take you to that variable, which also shows you ever other variable in the object. After you figure out what data you are after you can just hit back to go to the object you were editing.

Uh...thats all the fantastic stuff I've discovered about uibuilder that I can think of.