1327644 - Theme switching mechanism always scrolls tabs as close as possible to the end to keep selected tab visible

Status: NEW

(Firefox :: Tabbed Browser, defect)

Description

[arni2033]

>>>   My Info:   Win7_64, Nightly 49, 32bit, ID 20160526082509
STR_1:
1. Open many tabs to cause overflow in tabs toolbar. Let say you opened N tabs. Open N+5 more tabs.
2. In (N+5)th tab open url  https://addons.mozilla.org/en-US/firefox/addon/outlook-2013-blue/
3. Scroll the tabs strip so that selected (N+5)th tab was in the middle of visible part
4. Hover mouse over button "Add to Firefox"

AR:  Tabs strip is scrolled so that selected tab became last visible tab
ER:  Tabs strip shouldn't scroll: selected tab is already visible (See Note)


STR_2:
1. Open many tabs to cause overflow in tabs toolbar. Let say you opened N tabs. Open N+5 more tabs.
2. In (N+5)th tab open url  about:addons
3. Scroll the tabs strip so that selected (N+5)th tab was in the middle of visible part
4. Enable developer edition theme

STR_3:
1. Open many tabs to cause overflow in tabs toolbar. Let say you opened N tabs. 
2. Open customize mode. Open N+5 more tabs. Select tab with customize mode
3. Scroll the tabs strip so that selected (N+5)th tab was in the middle of visible part
4. Click button "Themes", then click any new theme to apply it


Note:
 I already described expected result, but actually, my personal expectations are more than just that.
 If selected tab is located before visible tabs, then "scroll into view" mechanism (which is obviously
 called in theme switching code) should scroll tab strip to make selected tab the FIRST visible tab.
 If selected tab is located AFTER visible tabs, "scroll into view" should make it the LAST visible tab