I made some improvements/changes to this simple but useful indie and figured I'd share them. Thank you to the original author for the starting point.
Changes from the original DayOfWeek
Removed native OnRender call (base) - Not needed and wastes resources
Changed so brushes are created and disposed of just once, rather than on every call to OnRender
Changed so textformat is created and disposed of just once, rather than on every call to OnRender
Added an option to highlight one of the days in a different colour