Open src/quick/util/qquickvaluetypes.cpp from qtdeclarative's 5.6 branch in Creator and go to line 628. Then, press Ctrl+Shift+U to find its usages. Weird stuff starts to happen. I tried to show this in the attached video, but it's difficult to show what's going on. Basically, I'm trying to undo the "u" that was entered, then the cursor stops blinking for a while while I try to save, blah blah blah. Try it out and it'll probably exhibit some weird behaviour.