My company currently has a product which relies on a custom, in-house ActiveX control. The technology it employs (TWAIN) is itself cross-platform by design, but our solution is obviously limited to Internet Explorer on Windows.

Long term we would like to become cross-browser and cross-platform (i.e., support other browsers on Windows, support the Macintosh or Linux).

Obviously if we wanted to support Firefox on Windows I would need to write a plugin for it. But if we wanted to support the Macintosh, how do I attack that? Is it possible to compile a version of the Firefox plugin that runs on the Mac? Would I be remiss to not also support Safari on the Mac? Are there any plugins which are cross-browser on a platform? (i.e., can any browsers run plugins for other browsers)

Since TWAIN is so low-level to the operating system, I do not think Java would be a solution in any capacity, but I could be wrong.

What do people generally do when they want to support multiple platforms with a process that will need to be cross-platform and cross-browser compatible?