(Spinning this off of bug 1335885) we are working on running all of our tests on ubuntu 16.04 vs 12.04, and there are some new failures to look at: https://treeherder.mozilla.org/#/jobs?repo=try&revision=5ac0bd83bb7cd8ba2ecad1571c4d2038d8a70ba4&filter-searchStr=mochitest-e10s-8&selectedJob=73652332 TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | An inner div should be the target of the event - got "INPUT", expected "DIV" TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | the target div should be the editor div TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | An inner div should be the target of the event - got "INPUT", expected "DIV" TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | the target div should be the editor div TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | An inner div should be the target of the event - got "INPUT", expected "DIV" TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | the target div should be the editor div TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | An inner div should be the target of the event - got "INPUT", expected "DIV" TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | the target div should be the editor div TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | An inner div should be the target of the event - got "INPUT", expected "DIV" TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | the target div should be the editor div TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | An inner div should be the target of the event - got "INPUT", expected "DIV" TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | the target div should be the editor div TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | An inner div should be the target of the event - got "INPUT", expected "DIV" TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | the target div should be the editor div TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | An inner div should be the target of the event - got "INPUT", expected "DIV" TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | the target div should be the editor div TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | An inner div should be the target of the event - got "INPUT", expected "DIV" TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | the target div should be the editor div TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | An inner div should be the target of the event - got "INPUT", expected "DIV" TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | the target div should be the editor div TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | An inner div should be the target of the event - got "INPUT", expected "DIV" TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | the target div should be the editor div TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | An inner div should be the target of the event - got "INPUT", expected "DIV" TEST-UNEXPECTED-FAIL | layout/forms/test/test_bug549170.html | the target div should be the editor div

This patch fixes the issue for me -- just shifting the synthesized clicks 2px downwards & rightwards. (+1px isn't sufficient, but +2px is) I'm pretty sure the problem is that the synthesized clicks are hitting the (curvier-on-recent-ubuntu) textarea/textfield-borders, and really they're intended to hit the actual inner editable area. The current synthesized click target (5px, 5px from the element's origin) seems pretty arbitrary anyway, so I think 7px,7px is just as good and is a bit more reliably inside the textarea, apparently.

Comment on attachment 8835872 [details] Bug 1337466: Adjust click position in test_bug549170.html to more reliably target editable area of textfield, rather than its border. https://reviewboard.mozilla.org/r/111442/#review112764

Pushed by dholbert@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/ef9db85bfdd7 Adjust click position in test_bug549170.html to more reliably target editable area of textfield, rather than its border. r=mats