(This is being sent to the WHATWG list, rather than the CSSWG list, as it seems like the sort of thing that should be primarily defined in HTML, with a CSS spec just referring to the HTML definition, like :active and similar things.)
Webkit has for some time now supported using the -webkit-canvas() function in CSS anywhere you could use an image (<http://webkit.org/blog/176/css-canvas-drawing/>, published in April 2008). The function takes an ident, which can then be used in the window.getCSSCanvasContext() function in javascript to grab a context keyed to that ident. Drawing on that context is then reflected everywhere on the page that references that canvas. In essence, this is defining a scriptable paint server, which seems useful enough that we'd really like it in the platform. I'm willing to define a canvas() function in the CSS Image Values specification, but since this relies explicitly on an HTML feature, it feels like the full definition should exist in the HTML spec. Thoughts? ~TJ
