Freeze image while selecting rectangular area

[bergkvist]

When taking a screenshot of something that might change, it would be a lot better for user experience and predictability if the image was frozen while drawing out the selection.

Snipping Tool for Windows, as well as Flameshot does this.

In practice, this means the entire screenshot is captured on mouse down. When releasing the mouse button, the full screenshot is cropped according to the selection.

Right now, the capture/cropping happens at the same time: when releasing the mouse button.

[DamirPorobic]

Yeah, we have similar functionality already in the snipping area widget for the the case that the compositor is disabled as in that case the snipping area can't be transparent so we take a screenshot and show it as the snipping area background. We might add a toggle to switch between those two behaviors as IMHO the current implementation works better with the delayed capture. But I do see the use case.

[DamirPorobic]

Added new config option for switching between freezing image when selecting area or not.

When we freeze the image the area selection is show after the delay (if any delay was configured) and when we do not freeze it, the area selection happens before the delay.

Currently we support it only for non wayland based implementation.