Here's a descriptions of where resources were spent in Netbeans 3.6 development:

GlennHolmer: There were big changes in the user interface for 3.6; are more changes planned for 4.0?

Ian Formanek: Definitely. 3.6 focused on 2 major things: the use of Windows L&F on Windows 2000 and XP (and updating the NetBeans design to look cool under those L&Fs), and introducing a brand-new window management system to streamline the way the IDE fits into the natural workflow of development.

Great. Half the advances of the xplat IDE fell under tweaking a cross-platform GUI API to look like a native GUI toolset on one platform. Way to go! Efficient!