What pray tell is a "native" application supposed to look like?
... like the other applications on that platform. It's really not a hard concept. Go look at other professional applications that were built specifically for each platform. Your product should look like *that* on each particular platform.
Ideally, on Gnome, it should look like it was written to run on Gnome. On KDE, like it was designed for KDE. On OSX, like it was made by Apple to run on OSX, and yes, on Windows, it should ideally feel like it was made by Microsoft for that particular version of Windows. Obviously that's an ideal that won't be met perfectly on all platforms. There will be compromises. But I don't think the concept is hard to understand.