I found a problem when editing a table of contents, on the second tab you can edit the structure of the entrys.
If the entrys are too large, because you added e.g. an additional tab, there are arrows to scroll left and right. But this doesn't work for me! See also screenshot: http://s14.directupload.net/file/d/2702/hxxrn3fm_png.htm
I confirm this behavior. Left arrow work, right arrow doesn't work. Nasty UI bug...
As a workaround you can use the keyboard arrows.
Duplicate of 'Bug 40948 - UI · EDITING: Hyperlink on page number in a Table of contents'
*** This bug has been marked as a duplicate of bug 40948 ***