The current primitives rect, line, circle and text lack capabilities.
it would be awesome to add more optional capabilities to devices.
e.g. SVG and PDF both support hyperlinks and gradients, which could degrade elegantly for e.g. the PNG device (by rendering normal text and a pixel-perfect gradient instead)
gridSVG shows what might furthermore be desirable: https://sjp.co.nz/projects/gridsvg/