Pretty sure these have been failing all along since the GTK+3 switch for ASan, but we've been ignoring them in the midst of the failure messages for bug 1204897 and bug 1221919. https://treeherder.mozilla.org/logviewer.html#?job_id=2977026&repo=mozilla-central

This looks a lot like bug 1221919, so I suggest we apply the same workaround as you used there.

Indeed, the "Expected...but got" screenshots show diagonal-lines vs. dots on the resize grabber.

Comment on attachment 8706297 [details] [diff] [review] Disable resizing of textarea to work around unreliable Gtk3 rendering of the resize grabber Review of attachment 8706297 [details] [diff] [review]: ----------------------------------------------------------------- > Bug 1235970 - Disable resizing of textarea to work around unreliable Gtk3 rendering of the resize grabber. r?dholbert As in bug 1237355, please mention the name of the testcase (or just "in a mochitest") in the commit message. Otherwise, this gives the impression that you're actually changing how <textarea> works in general. r=me with that

https://hg.mozilla.org/integration/mozilla-inbound/rev/21fcc39026407623cf9cf195d493e1af0b5b3097 Bug 1235970 - Disable resizing of textarea in mochitest test_bug582181-2 to work around unreliable Gtk3 rendering of the resize grabber. r=dholbert