the tabs are very independent.
Open New Tab. Make an edit in one tab. The edit does not appear in the second tab until 1. lexicons are saved in the first tab AND 2. Reload current tab is used in the second tab.
Did you notify the users about this behaviour? I am afraid that anyone will hardly understand the behaviour until he learns that each tab is actually on offline web application with a single online functionality (save lexicons).
The tabs can make even further confusion if the above behaviour interferes with issue #77.