User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Firefox/38.0 Build ID: 20150525141253 Steps to reproduce: Steps to reproduce: 1) Be using a Linux OS 2) Hover the mouse over an <select> element that contains a title attribute in an <option> dropdown 3) Wait for a tooltip to appear Here is a very simple example of an <option> dropdown with <select> elements that contain the title attribute: http://jsfiddle.net/lsabota/bt3x780j/ Actual results: With firefox developer edition 40.0a2 (2015-06-29), no tooltips appeared on my system. I have tested with both RHEL 6.4 64bit and Arch Linux 64bit and I am experiencing the same issue. I tested this same scenario on Windows 7 with 40.0a2, and the tooltips appeared. FWIW, the tooltips appear fine in firefox 38.x on RHEL 6.4 and Arch Linux Expected results: I would have expected a tooltip to appear that contains the value of the title attribute of the select element.

I can reproduce the problem on windows7 with e10s on, but not with e10s off.