unlock mouse from center when panning

[Boumtchack]

Link to issue number:

fix #19708

Summary of the issue:

Mouse was kept in the center of the screen even if the settings was set on false

Description of user facing changes:

Keep mouse centered works properly with panning

Description of developer facing changes:

adding 2 function to better manage panning and mouse center

Description of development approach:

used better condition to update magnifier.

Testing strategy:

Manual

Known issues with pull request:

Code Review Checklist:

• Documentation:
  • Change log entry
  • User Documentation
  • Developer / Technical Documentation
  • Context sensitive help for GUI changes
• Testing:
  • Unit tests
  • System (end to end) tests
  • Manual testing
• UX of all users considered:
  • Speech
  • Braille
  • Low Vision
  • Different web browsers
  • Localization in other languages / culture than English
• API is compatible with existing add-ons.
• Security precautions taken.