According to this post:
There's an option to create an Hybrid Extension.
Has anyone here tried it?
How hard is to transfer parameters from the Panel to the C function?
Could we use the main view as preview?
You don't say which app you are developing for.
In InDesign, the easiest way to handle hybid plugins is by making your plugin scriptable ad reading/writing to the scripting interface in ActionScript. Calling funtions in the plugin from C++is possible as well, but I've not had the need.
Other apps are less scriptable, so it might be a little more work, but there's sample projects included inth SDKs.