This is not a bug per se however it is a serious ergonomic issue (my crippled last 3 fingers can vouch for it)
On the fields tab. There are many things going on there. The scrolling width area is too narrow: a hand doesn't go straight up, that is why on windows explorer, once you "grabbed" the scroll bar cursor, as long as you keep the left button pressed, you can scroll up and down with a deviation buffer of about 2 inches. 2" is probably too much but 5/16" is too small. Watch the video.
if one deviates to the right, the scrolling gets interrupted by the resizing arrows. If you deviate to the left, you risk bumping into a hot zone and drag field elsewhere (hot zone being the field type menu when the field is highlighted (selected)).
It really forces you to slow down or make mistakes. If you see that you grabbed a field (mouse arrow has a + sign (which freaked me out at first because i thought i was duplicating the field)), you can't just do ESC to release the grab. And of course CTRL+Z doesn't reverse a change you made inadvertantly.
See video for the struggle in action.
On the image below, you see how narrow the scroll area is, where orange is some deviation possible sometimes but if you encounter a hot zone (purple) you are doomed