Allow disabling of red borders of selected PolygonLabels

**Is your feature request related to a problem? Please describe.**
When a PolygonLabel is selected, the borders turn red to indicate that it has been selected. It can be confusing if there are other labels that are red coloured.

**Describe the solution you'd like**
Allow an option to disable the change of border colours upon selection, and show only the resizing box on select.

**Describe alternatives you've considered**
Using style to change the border colour, but it doesn't work.

**Additional context**