I haven't used Eclipse in a decade, so maybe it's changed, but back then it was very much a Java UI, not a native feeling one.

I remember the Java UI, but at some point they switched to a version of Swing that made it look more native, at least on Linux.

	▲	cowlevel a day ago \| parent [-]
		Eclipse uses SWT which uses real native controls. Of course Linux doesn't have native controls - I think it uses GTK on Linux.