Draws filled rectangle of given color
Note even if this class has the 4 drawing methods then it is not a Graphics context and never will be. The 4 drawing commands are more of to help make debugging easier.
When used with color space CMYK then the fill color is no longer RGB but CMYK, and is passed in like &cFFFFFFFF, where first 2 hex letters are C, 2nd 2 are M, next pair is Y and last pair is Key.
This method does nothing on 16bit per channel bitmaps.