User Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:29.0) Gecko/20100101 Firefox/29.0 (Beta/Release) Build ID: 20140506152807 Steps to reproduce: I opened Firefox for developing reasons with my WebApp. I opened the Console on the left monitor (i have 2). In fullscreen. I use Windows 8.1. I switched to the tab "Debugger" and also showed the console split. (At the bottom of Firefox) If i type now, the Intellisense for the Console moves Down fast (glitches), so i cant read annything. Sometimes the intelisense popup even appears on the right screen (my main monitor). Actual results: THe Intellisense glitches down from the generated position out of the window, so i cannot read it. Expected results: The Intellisense should have stayed (on the same window) ^^

Pretty sure this is a dupe. Currently only able to find bug 961431 which was fixed in Firefox 28. Going to mark this as New and see if QA can help us either reproduce this or find a dupe. Thanks for filing!

maybe bug 967096 ?

This bug is dupe of bug 967096 which is clearly more elaborated than this one.