For heaven's sake you can disable this in the configuration settings.

ColinDabritz · on June 2, 2014

How bizarre that they realized the issue, fixed it, and left it off by default. I can't think of one reason to leave the old behavior in.

The problem here is http://en.wikipedia.org/wiki/Fitts's_law

This means that "one little pixel" is essentially infinitely high for purposes of mouse selection, and it makes hitting tabs much easier in this case.

chr1 · on June 2, 2014

It's not that simple, if i want to move a tab i don't want to move any random tab, so i still have to aim horizontally, and effect of Fitts's Law is much smaller. I for one never tried to drag a tab from top one pixel. On the other hand for dragging a window horizontal precision doesn't matter much, and that one top pixel is really useful.