I don't know if I'm the only one, but when I have to select controls just for the purpose of changing properties, it often happens that I unintentionally move the control a bit. If I notice that, I can press Undo, but if I don't the control isn't properly positioned anymore.
What I would like to suggest to have a setting that, if checked, wouldn't allow moving controls unless I also hold some key like the Option or Command key.