User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:59.0) Gecko/20100101 Firefox/59.0 Build ID: 20180323154952 Steps to reproduce: Have at least 3 tabs open. Close the middle tab by clicking the close tab button [X]. Actual results: The tab to the right of the closed tab is selected as the current tab. Expected results: The tab to the left of the closed tab should be selected as the current tab. More often than not, the tab on the left launched the one on the right so you would want to return to it. This is how it used to work in previous FF versions. At the very least, this behavior should be configurable in about:config. There's an add-on called 'Select After Closing Current' that allows this behavior to be configured, but it is flawed since FF still selects the tab on the right before the add-on switches to the one on the left.

Updated Steps to reproduce on FF with no add-ons: Using about:config, set browser.tabs.selectOwnerOnClose to false. This setting only applies to a newly opened tab. The behavior I'm talking about is with tabs that are already open. Have at least 3 tabs open. Select the middle tab. Close the middle tab by clicking the close tab button [X].

(In reply to owenw4rd from comment #0) > This is how it used to work in previous FF versions. I tried 52 and 28 and both switched to the tab on the right. What version worked differently? > There's an add-on called 'Select After Closing Current' that allows this > behavior to be configured, but it is flawed since FF still selects the tab > on the right before the add-on switches to the one on the left. Same issue with Activate Left Tab on Close. It must be an API problem. https://addons.mozilla.org/firefox/addon/activate-left-tab-on-close/

> I tried 52 and 28 and both switched to the tab on the right. What version worked differently? Maybe I got the idea from using the now obsolete 'Tab Mix Plus' add-on, which I think allowed configuring tab close behavior. Either way, I think it should be about:configurable or just make the tab to the left the default tab to select.