Have a look at SWT. It's the best way to do Java UIs IMO. I don't know why it isn't more popular. It uses the native UI kits internally, so it feels and is 100% native.
Exactly. Try using SWT to do anything like CoreAnimation on the mac with either similar programming ease or buttery results. There's a reason why one should go native for anything beyond a database viewer.
100% native on Windows maybe (and even there it depends on the Windows version). On the Mac it's like a foreign object.
And that's for the more basic widgets -- more advanced widgets have custom implementation from primitives in SWT, so they are hit and miss with regards to native look and feel.
