Firefox Nightly 29.0a1 2014-01-17 on Windows 8.1 Pro 64 bit When there are more tabs than the tab bar can show at once, the user can click/tap on 'left' and 'right' buttons to move the tab list one item to the left or right. Double-clicking advances the list so that all visible tabs get moved out of view and the next set gets visible. If you want to move 2 tabs to the left, you will click twice on the left button, but Firefox Metro often recognizes this as double click. It seems that the time delta between two click events can be longer in Metro than on Desktop to be sufficient to regard it as a click event. This is likely due to touch events. Please add different double click/tap rules for input devices like mice and touch screens.

Are you testing use a mouse or touch? Double tap delays are controlled by the system via the Windows control panel.

I use a mouse and after reconsidering, I think I simply click again too early on the button. Feel free to set this bug to 'invalid' or morph it into 'let users easily go a few tab to the left or right in the tab strip'.

We're going to be overhauling the tab bar in a future release, so lets get this issue included there so it can be addressed.

Mass close of bugs in obsolete product https://bugzilla.mozilla.org/show_bug.cgi?id=1350354