Up until fairly recently the popup that appears when hovering the mouse over a tab stack showed the tab thumbnails in a grid of various dimensions, depending on the number of tabs in the stack, e.g.
+---+---+
+---+---+
+---+---+
+---+---+
Now the behaviour seems to be to show all the thumbnails in a single column:
+---+
+---+
+---+
+---+
+---+
+---+
+---+
I would prefer the former behaviour. Does anyone know how this might be achieved?