STR: (Win7_64, Nightly 44, 32bit, ID 20150924030231, new profile, safe mode) 0. Make sure you have some text copied to clipboard, e.g. "They're taking your beta-testers to Isengard" 1. Open Firefox 2. Press Ctrl+Alt+Shift+I to open Browser Toolbox (make sure you have all those stuff enabled) 3. Click Debugger tab in the Browser Toolbox 4. Switch back to Firefox window 5. Press Ctrl+N to open new window 6. Focus location bar and press Ctrl+V to paste the text from clipboard Result: Text is doubled. Actually sometimes I see (when firefox lags and does everything slowly) that when I press Ctrl+V, the text is pasted OK, but after 2-3 seconds the same text is pasted the second time w/o any input. Maybe it's a special case of some major bug Expectations: Text should be pasted 1 time