When you move your mouse to an editor tab and go just below the tab button you will see a point slightly outside the tab
where the orange highlight comes on top and you click the editor does not change to this tab. The tab appears to take
the click but not switch to it. If you double click or drag from this spot though it does affect that tab.

It looks like the IDE needs to adjust the lower bounds of the tab button so it is within the boudries of the button.
Also note that if you keep moving your mouse up to the very bottom of the button it still doesn't handle the single
click either. It highlights the tab button though, making you think it will.

I hope I explained this properly.

Thanks.