[Affected versions]: - 62.0b18, 63.0a1 (2018-08-20) [Affected platforms]: - Win 10x64, Ubuntu 18.04LTS, macOS 10.11 [Steps to reproduce]: - have at least 2 search engines added in the top-sites section 1. Launch Firefox; 2. Open the new-tab page; 3. Click on any search engine; 4. Middle click on any other search engine. [Expected result]: - search and shortcut is performed with the desired search-engine; - the search engine mentioned at step 4 is highlighted only; [Actual result]: - the search engine from step 3 is highlighted on middle-click [Regression range]: - mozregression bisection points out to: https://bugzilla.mozilla.org/show_bug.cgi?id=1481590 - pushlog url: https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=7a3737f257d51c78110bbab40017dbb593410518&tochange=d0d2e0f4b33cd28bc05c353c185873256f7f926e - last good: 2018-08-15 02:59:42.528000 - first bad: 2018-08-15 04:05:24.898000 [Additional notes]: - attached recording with the issue

Tim, how important is this regression? Thanks!

Hey Mike, As someone without a middle mouse button, i dunno! I'm marking it 'uiwanted' and we will get an answer soon, though it's safe to say we can't get anything done for 62.

I can confirm the issue but it does not seem important enough to address. The functionality is correct: the search keyword you click is added in the address bar. The glitch is only visual and clicking on a topsite with the mouse wheels seems like an accidental action not an intended one.