>>> My Info: Win7_64, Nightly 49, 32bit, ID 20160526082509 STR_1: 1. Open url [1] in a new tab 2. Click on the page [new tab will open] 3. In less than 3 seconds, start dragging selected tab, move mouse to the center of the screen 4. Wait 3 seconds 5. Release left mouse button (or press Escape - doesn't matter) 6. Try to drag selected tab (bonus - there's already bug, but you can continue) 7. Middle-click selected tab 8. Press Ctrl+Tab several times to switch to another tab 9. Repeat Steps 6-7 AR: Step 6 - nothing. Step 7 - new about:blank tab opens. Step 9 - the same results ER: Step 6 - tab should follow mouse pointer. Step 7 - tab should close. Step 9 - the same > [1] data:text/html,<script>onclick=function(){var W = window.open("http://example.org"); setTimeout(function(){W.close()},+I.value); }</script><input id="I" value="3000">

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:53.0) Gecko/20100101 Firefox/53.0 I have tested this issue on Windows 10 x64 with the latest Firefox release (50.1.0), latest Nightly (53.0a1-20170104030214) and also on the Nightly specified by the reporter and haven't managed to reproduce it. After loading the url [1], clicking on the page, and in less than 3 seconds, dragging the tab and waiting 3 seconds, when releaseing the mouse the tab is moved to the desired place(5) and when trying to drag the selected tab, the tab is dragged to the desired place(6), also on step 7 the tab is closed. Marking this as Resolved - Incomplete due to the fact that I cannot reproduce this issue and the reporters account is disabled. If anyone can still reproduce it on latest versions, feel free to reopen the issue and provide more information.