Hi! Might I suggest to use macro_optional_find_package() to detect presence of Marble? From a packaging point of view it would be more elegant to be able to avoid opportunistic dependencies on large and complex projects like Marble.
The reason: Marble is one of a tiny set of applications that try very (too) hard to be as Mac-like as possible when built on Mac, and has a build system that forces a standalone (= all-inclusive) app bundle on that platform. This means that the Marble library cannot be found and most likely not even be shared with other applications. It's not impossible to patch the build system to provide choice during the Marble build, and this is what I've done a couple of times to create a proper MacPorts package, where Marble's shared resources go into their traditional designated locations. I've put that patch up for review, but have had no feedback on it at all. As a result of that lack of interest for being able to use the Marble library in other apps (on Mac), and also because the patch requires refactoring at almost every update I am considering seriously to drop the port. Cheers, René PS: Google Earth can be driven by external apps IIRC, and it's even possible to open Google Maps in a browser with a set of GPS co-ordinates. Maybe it wouldn't be too hard to use that in a fallback plugin?
