Circular Area Plugin for OpenTabletDriver 
Circular mapping for tablet areas.
Quick start guide:
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Install Circular Area from the OpenTabletDriver plugin manager.
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Enable one of the Circular Area mappings in the filters tab and apply the setting.
Recommended mappings: FG-Squircular Mapping, FG-Squircular Mapping Inverse, Elliptical Grid Mapping, or Elliptical Grid Mapping Inverse.