After a brief discussion with Humphrey, it seems that the URL bar can be quite useful. Perhaps we shouldn't take it out.
This project's ultimate potential may be as a tool that runs games across multiple platforms. I could create a game, send you a copy, and all you'd need to run it is a computer and the portable canvas program.
Herein lies a bottleneck. If the portable canvas can only grab canvas demos from c3dl.org, then all games must be approved before appearing on c3dl.org and consequently must be approved to be distributed to portable canvas users.
On top of this, games may require a connection to a database server to provide a character-building element. The SQL queries must be contained in an html; it'd be ridiculous to ask the canvas element to do SQL.
If portable canvas keeps its ability to navigate to URLs outside of c3dl.org, we can solve the distribution problem. Users can host their solutions on their own servers and simply provide the URL.