Block diagram won't scroll. Need to bring back to (0,0) origin

I noticed that I couldn't scroll the block diagram anymore to the left. Then I saw the coordinates, and it shows (-32172, -4250).

I must be way too far to the left. Then I right to scroll to the right, but putting the mouse cursor on the horizontal scroll bar, and that didn't work.

Then I Shift-right-clicked to get the little hand to pan to the right. Not even that was successful. My BD is not that big. I used the Clean Up Diagram

tool and I don't see any control or indicator that is way to the right or left. Why can't I scroll to (0,0) origin?

On a side note (possibly related), does having Tab Control on the FP cause strange behavior? If so, why Tab Controls exist?