The IntelliJ stuff is Swing IIRC, but not open source. jEdit, IIRC, was often mentioned as a properly written java GUI app, I think it's Swing, but I might be

The IntelliJ stuff is Swing IIRC, but not open source. jEdit, IIRC, was often mentioned as a properly written java GUI app, I think it's Swing, but I might be wrong. EDIT: IDEA code is apparently open https://github.com/JetBrains/intellij-community https://github.com/JetBrains/intellij-community