When all dialogs in tabs cannot be displayed in a window,
2 small arrows are available to scroll the tabs horizontally.
The problem with those arrows is that they select the next
tab title (on the left or on the right) without selecting the
tab itself.

For example, consider a window with 5 tabs in total (numbered 
from #1 to #5), #1 to #4 are visible and the current tab is 
#1. In order to select #5 (currently invisible) the 
following actions are required

 - click 4 times on the right arrow in order to make #5 visible.
 - move the mouse cursor and click on #5.

I think that the arrows behavior should be changed to one of the
following:

 - select the next right or left tab (instead of hilighting it).
or
 - shift all tabs to the right or the left.