1327112 - Tabs resize/move inconsistently when I move mouse over empty area in tabs toolbar

Status: NEW

(Firefox :: Tabbed Browser, defect)

Description

[arni2033]

>>>   My Info:   Win7_64, Nightly 49, 32bit, ID 20160526082509
STR_1:  (titlebar disabled)
1. Open as many tabs as possible w/o causing overflow in tabs toolbar (N tabs total)
2. Hover mouse over (N-3)th tab, press middle mouse button 3 times to close 3 tabs
3. Move mouse to the center of the empty area in tabs toolbar (to the right by ~200px)

AR:  Tabs resize/move to the right to take all space in tabs toolbar


STR_2:  (titlebar enabled)
0. Open customize mode, enable titlebar, close customize mode
1. Open as many tabs as possible w/o causing overflow in tabs toolbar (N tabs total)
2. Hover mouse over (N-3)th tab, press middle mouse button 3 times to close 3 tabs
3. Move mouse to the center of the empty area in tabs toolbar (to the right by ~200px)

AR:  Tabs stay still


ER:  One behavior in both cases. Either X or Y
 X) STR_1, STR_2 - tabs should stay still, just like in GoogleChrome
 Y) STR_1, STR_2 - tabs should resize/move to take all space in tabs toolbar


Note:
 I don't know which behavior is better - X or Y. But in case of (X) there's further bug regarding tabs
 resizing: if you add Step 4 to STR_2 "Click new tab toolbarbutton", then as a reesult of that step,
 new tab opens, but it immediately moves away from under the mouse pointer, because tabs immediately
 reresize/move. Also, I used to (Y), because I use the browser with titlebar disabled (default config)