Using a QTableWidget with the following properties:
selectionMode: SingleSelection
selectionBehaviour : SelectItems

uname -a:
Linux 2.6.32-34-generic #77-Ubuntu SMP Tue Sep 13 19:40:53 UTC 2011 i686 GNU/Linux
Ubuntu 10.04

In the itemSelectionChanged() slot I print the currentRow().

Then I do the following:
- click on a cell of the first row keeping the mouse button pressed - currentRow is 0 (OK)
- move the mouse without releasing the button on the next row - currentRow is 0 (KO - should be 1)
- move the mouse without releasing the button on the next row - currentRow is 1 (KO - should be 2)
- move the mouse without releasing the button on the next row - currentRow is 2 (KO - should be 3)
and so on...

The first movement of the mouse, selecting the next row, doesn't update the currentRow.
All the next movements increment the currentRow but it's not synchronized as it has lost one value in the first movement.