User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:45.0) Gecko/20100101 Firefox/45.0 Build ID: 20160414065514 Steps to reproduce: On Ubuntu Linux 16.04 , start firefox 45.0.2 with the standard x11 geometry settings: /usr/bin/firefox -geometry 1435x1632+166+25 Actual results: Firefox will place itself wherever it wants (usually the upper left corner of the screen); regardless of the provided x11 geometry settings. However, firefox appears to infrequently place its window at the correct screen location upon startup. I only saw it once after trying half a dozen times. Firefox had positioned its window incorrectly at first and then jumped to the correct position within a second. Expected results: As an application that works within x11, firefox should be following x11 windows option standards. Workarounds have been posted (see similar bug 492194). However, workarounds become time consuming to find, implement, and maintain over time. It is ultimately best for users if firefox played by the x11 rules if it wants to play in the x11 sandbox like a good application!