[Annotations] The crop selection can wrongly exceed the image area

[SoftVision-CosminMuntean]

[Affected versions]:

• Nightly 62.0a1
• Screenshots 32.1.0 dev

[Affected Platforms]:

• All Windows
• All Mac
• All Linux

[Prerequisites]:

• The "xpinstall.signatures.required" boolean pref is set to "false".
• The "extensions.legacy.enabled" boolean pref is set tot "true".
• Have the Screenshots 32.1.0 dev version installed from here, on a new clean profile.
• Have a saved shot link.

[Steps to reproduce]:

1. Open the Firefox browser with the profile from prerequisites and navigate to the saved shot link.
2. Click the "Edit this image" button.
3. Click the "Crop" button.
4. Start performing a selection and move the mouse diagonally until you hover the "Confirm" button.
5. Release the mouse and click the "Confirm" button
6. Observe the image.

[Expected result]:
Step 4: The selection remains within the image borders
Step 6: The image is correctly cropped.

[Actual results]:
Step 4: The selection exceeds the image borders.
Step 6: An extra background is displayed.

[Notes]:

• The issue is not reproducible after a selection was performed then resized.
• Here is a screen recording with the issue:
  

[chenba]

The fix for #4456 also fix this. But now the drag detection will stop as soon as the mouse cursor leaves the shot. It's awkward and different than the previous behavior.

[chenba]

I've filed #4458 as a follow up.

[chenba]

Fixed in #4468

[SoftVision-CosminMuntean]

I have verified this issue using latest Screenshots (32.1.0) dev version and is no longer reproducible. Tested on Windows 7 x64, Mac 10.13 and Arch Linux,