When I select there, if I pull away from the window it resizes and won't drag. If I move the pointer up-down on the right or left side, it moves the window and won't resize.

Which seems like a sensible and convenient choice to me.

Maybe it isn't working so predictably for you?

It's definitely neither sensible nor convenient. I expect it to trigger the scrollbar, not move the whole window. The only way one should be able to move the window is to drag the title bar. There's no reason clicking and dragging the 1px window border should ever move the whole window. Every Linux window manager, Windows, and IIRC Mac System <= 9 behaves this way.