Dear Gjallarenes,
Our main reservation for moving to Seaside 2.8 was the suggestion that Plotkit was not supported.
It appears that the main reason Seaside 2.8 does not directly support plotkit is that the canvas html tag had been removed and placed in the separate addon package "HTML5".
So I tested plotkit with the latest Seaside 2.8, and the HTML5 package and all appears to be well.
Keith
setools@lists.squeakfoundation.org