I am the author of Sailwave - a sailing scoring app for Windows. I want to move to a cross-platform solution.
Essentially Sailwave reads an XML file - presents a UI to edit the structure in various ways and writes it back.
Are user-scripts possible somehow or does it break sandbox security rules?
I've also been looking at Mono - apart from the learning curve (ug), the gtk# UI looks really old fashioned to my eyes - Air+jQuery would be so much sexier!
AIR can do what you want to do but with the restrictions. You might need to use the Security Sandbox Bridge for the type of functionality you want.