Frankly, I've never seen an editor which comes even close to what I can do manually in a text editor. All the visual editors are nice if you only have very simple needs like putting a few buttons in a window. When things become more complex, visual editors quickly loose their competitive edge.
I usually use a bunch of high-level classes built from more basic widgets and wire my UI from that. This also allows me to easily test my UI with automated JUnit tests (because I can control what the source looks like).
Lastly, changes to the UI won't generate unnecessary noise in the version control system.
