Currently, when the New Tab (+) button is pressed while viewing a webpage in Firefox for Android, the new tab is added at the end of the tab list.
Current tabs
Tab 1 | Tab 2 | Tab 3 | Tab 4
Current tab
Tab 2
Tab 1 | Tab 2 | Tab 3 | Tab 4 | New Tab
Tab 1 | Tab 2 | New Tab | Tab 3 | Tab 4
This would preserve the user's tab sequence and keep related browsing activity grouped together.
This suggestion only applies when a new tab is created while viewing an existing tab. In that situation, the new tab should be inserted immediately to the right of the currently active tab.
The global New Tab button in the tab tray can continue creating tabs at the end of the tab list, since there is no active tab context that should determine placement.
An optional setting could be provided for users who prefer the current behavior.