If a document is being recorded and a snapshot is taken, any 'actively selecting' tool will suddenly interrupt.
For ease of reproduction, set the recording interval to 5 seconds or so. Then, after making a change such as a brush stroke, try to make a selection using the box/circle/free/polygon selection tool.

What happens:
The selection stops, as if you lifted your pen.

Expected: 
The selection continues and it either delays the saving until after the selection, or saves in the background without interrupting the selection.