Sets the global stencil behavior.
The stencil buffer is an invisible drawing target that you can use as a mask for other drawing operations. For example, you might want to crop an image to a circle. You can do this by drawing a circle to the stencil buffer, then using that buffer as a mask while drawing the image.
In order to use stencils, you must be rendering to a target that was
created with a stencil buffer attached. To enable this for the main
true when creating your context. To enable this for a canvas,
initialize it via
set to true.