Adding a fix for igCheckboxEditor #1984

[valadzhov]

Closes #1984

Additional information (check all that apply):

• [x] Bug fix
  • [ ] New functionality
  • [ ] Documentation
  • [ ] Demos
  • [ ] CI/CD

Checklist:

• [x] All relevant tags have been applied to this PR
• [ ] This PR includes unit tests covering all the new code
• [ ] This PR includes API docs for newly added methods/properties
• [ ] This PR includes general feature table updates in the root README.MD
• [ ] This PR contains breaking changes
• [ ] This PR includes behavioral changes and the feature specification has been updated with them

[coveralls]

Coverage increased (+0.004%) to 83.995% when pulling f3af67a40c72351f755d5537f6bac1bd2d8214ed on valadzhov/fix-igCheckboxEditor-1984-18.2 into 55f3bd60e2f9b5c024e6086417137515cd6446b2 on 18.2.

[wnvko]

In GC when checkbox is focused the tick is still invisible. When checkbox loses focus the thick is visible.