User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.8) Gecko/20100722 Firefox/3.6.8 (.NET CLR 3.5.30729) Build Identifier: Mozilla/5.0 (Windows; Windows NT 6.1; rv:2.0b3pre) Gecko/20100729 Minefield/4.0b3pre This is exactly what you get with all tabs on Chrome. And it sucks. I know it's a very unlikely situation, but I'll upload a screenshot that shows exactly what happens when you open many app tabs, too many for the width of the window. There should be either a limit to app tabs, or they should have a % max-width for the tabstrip and have scroll buttons as normal tabs do. Again, I'll upload a screenshot right away. Reproducible: Always

You just can't see either all the app tabs or the normal tabs (I have like 4 or something normal tabs and like 10 more app tabs).

Maybe there should be a limit on the amount of app tabs a user can have. Or, we could have a scroller, like we do with normal tabs.

Users will likely have a strong preference as to how they use app tabs, and use cases will abound. We should make this as customizable as is reasonable. I like the thinking of doing a max-width (measured by some %), then scroll for any outside of that. However, some users might want to have a dozen app tabs, but only a few visible. If we do a simple max-width, the app tabstrip is likely going to be wider than they want. I think the best solution might be to add a grippie between the app tabstrip and the normal tabstrip so the user can size it as they want. The app tabstrip should have a min-width wide enough for two app tabs. Since resizing wouldn't be an option if the user has < 3 app tabs, no grippie until there are 3 or more.

The Tab toolbar is customizable so any plans you devise should not assume that the tab strip extents across the full width of the toolbar/window.

cant we have separate "app"-tab scroll for apptabs , further apptabs wont be more than say 20...

This still happens in the latest Nightly, except it the toolbar below jitters and flashes.

Flickers between this and "normal" state

Comment on attachment 543642 [details] Another screenshot on Nightly Only happens when there are no "normal" tabs

This is still an issue as of Firefox 62. It would be nice to have a scroll like Josh said before.