1497304 - The tab "close" button cannot be clicked if there are enough tabs open

Status: RESOLVED DUPLICATE of bug 1496491

(Core :: Web Painting, defect)

Description

[Pomax]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:64.0) Gecko/20100101 Firefox/64.0

Steps to reproduce:

STR:
- open 50+ tabs with the browser at 1500x1000 (it works for any other resolution, I'm just using that while filing this bug). I recommend https://imgur.com/r/redpandas and just opening all thumbnails in new tabs with a ctrl-click
- scroll to the right end of the tabs bar
- place mouse cursor over tab close button
- start clicking the close button for the rightmost tab. The browser will "auto-shift" the tabs so that you can continue clicking to close more tabs



Actual results:

Either immediately, or after a few repeated clicks, the close button suddenly doesn't work the way it's supposed to at all, either not registering a click, or not even registering the cursor being over it, acting like plain browser chrome (at best it does nothing, at worst it suddenly maximises/restores the browser)


Expected results:

the close button should behave like the close button should behave.