Can't change the Layer's frame thickness

[magau]

Check the full description in QGIS Closed issue: Freehand raster georeferencer plugin creates a border around every image #45004.

My proposed solution is to add a slide bar bellow the already existing one used to control the Layer opacity, to control a frame_thickness property that would be used in the following instruction.

pen.setWidth(frame_thickness)

Reference file: freehandrastergeoreferencer_layer.py