Abandon scroll when mouse moves away from scrollbar

The scroll bars do not behave like normal scroll bars in windows.

Steps to reproduce:
1. Open a file with enough lines to allow vertical scrolling
2. Drag the scroll thumb up or down to scroll
3. While still holding the mouse button down, move the mouse left away from the scroll bar

Expected behaviour: the scroll should be abandoned and the view position of the file should revert to where it was before the scroll was started

Actual behaviour: the scroll is not affected

It's common in most other apps (on windows at least) to be able to scroll to view content off-screen and then move away from the scroll bar to revert to the initial position. This prevents the user from needing to search for their initial position (frustrating!).

Thanks for your consideration!