Because I really used to enable the 'Documents tab' row AND Tile windows horizontally/vertically.
I know that Tab grouping could be a nicer replacement but:
-I want to tile _uniformly_ three or more docs.
-When the 'Document Tabs' are enabled, the Synchronize Scrolling is lost.
![Confused :?](./images/smilies/icon_confused.gif)
And the other choice to simulate 4.x (activating the Document Selector) occupies too much space against the simple old tabs' row...
Thanks,
jugaor