1326839 - Tabs twitch by 15px when I drag and drop tab to beginning/end of tabs toolbar

Status: NEW

(Firefox :: Tabbed Browser, defect)

Description

[arni2033]

>>>   My Info:   Win7_64, Nightly 49, 32bit, ID 20160526082509
STR_1:
1. Open new window. Open many tabs in that window to cause overflow in tabs toolbar. Select last tab
2. Drag and drop the leftmost visible tab to the right scrollbutton in tabs toolbar

AR:  All tabs twitch by 15px to the left. The last tab (selected) is cut off by 15px
ER:  Tabs shouldn't twitch. Selected tab should be fully visible when I drop it


STR_2:  (further experiments)
1. Open new window. Open many tabs in that window to cause overflow in tabs toolbar. Select last tab
2. Drag the leftmost visible tab to the right scrollbutton in tabs toolbar
3. Drag the dragging tab a bit to the left, to make it penultimate tab. Drop the tab

AR:  The last (background) tab is cut off by 15px
ER:  Tab strip shouldn't randomly twitch in the last moment. Please.

Note:  This is australis regression. Oh, and also this is a good way to reproduce bug 1260222.

Comment 1

[YF (Yang)]

I see these problems in Fx29.0 & 20160526082509, on Win10.