Pen highlight for drawing on images

Requesting a feature...

When drawing over an image, the pen colour can easily blend in and get lost. In the past I've solved this by adding a 'highlight' colour, which is different from the pen. The contrast allows the new markings to standout better. The way I did it previously was for the 'highlight' colour to be drawn first, and be a number of pixels wider than the pen colour.

Would be cool if this library had something like that, especially since you've got colouring over images in the ReadMe.