The selection's coordinates are wrongly displayed with negative numbers when it's performed backwards

[SoftVision-CosminMuntean]

[Affected versions]:

• Nightly Try Build with Screenshots 33.0.0

[Affected Platforms]:

• All Windows
• All Mac
• All Linux

[Prerequisites]

• Have the Nightly Try build with Screenshots 33.0.0 installed from here.

[Steps to reproduce]:

1. Open Nightly Try build and navigate to any website.
2. From the "Page Actions" menu click the "Take a Screenshot" button.
3. Perform a selection from the center to the left corner of the page without releasing the mouse.
4. Observe observe the displayed coordinates.

[Expected result]:

• The coordinates are correctly displayed with positive numbers.

[Actual results]:

• The coordinates are displayed with negative numbers.

[Notes]:

• The width's coordinates are displayed with negative numbers when performing a selection from right to left.
• The hight's coordinates are displayed with negative numbers when performing a selection from the bottom to the top.
• The issue is not reproducible with Screenshots 32.1.0 or older versions.
• Here is a screen recording with the issue:
  

[SoftVision-CosminMuntean]

I have verified this issue on latest Screenshots (33.0.0) dev version installed on latest Nightly (62.0a1) build and the issue is no longer reproducible.
Tested on Windows 7 x64, Arch Linux 4.12 and Mac 10.13.