Thanks very much.
I know how to do it via Windows, but if we start programming in Windows SDK instead of Ruby, this is less fun, and more important, additional headaches for deployment.
One suggestion would be a few members of the sites, knowledgeable in system programming (Windows and Mac) group their efforts to build a utility libraries (dll) to complement the Ruby API of Sketchup (menu, events in tools, mouse, etc...). Unless the Sketchup SDK is more powerful!