Not sure, whether anyone else observed this.
I have a quite big GWT application and always do the compilation of all classes via ant. In IntelliJ, the respective output folders for the project's modules are defined (some target-folders within the project).
When starting the GWT application (via GWT configuration), the application occasionally starts (re-)compiling, although it should not as the ant-task already has done it.
If it does so, the class files it produces get stored into the source folders of the respective java files (causing some thousands "Unversioned files").
Is there any option to set the output folders for GWT support?
[GWT] Compilation process files classes into source folders