Why are the Roadmap edit limited to 980x500 px?

[Johan Grimm]

The Roadmap tool creates a clear overview but I find the edit view itself a real pain to work with. The standard edit "window" is har limited to 980x500 px. Why?

I believe most can live with 980 px width but a lot of the clarity in the planning itself is totally lost by the 500 px height limit. My screen is 1680x1050, the area used by the web page itself is 1680x794 px i.e. the edit view uses only around 60% per direction.

A full blown "drag window" is not needed but would it be possible to add some sort of "user setting" in percentage of screen? Applicable for many other edit view...