There is no indication the *.gui files was changed and needs to be saved.
Steps to reproduce:
- create GuiBuilder form: mvn cn1:create-gui-form -DclassName=com.example.MyForm
- open GuiBuilder: mvn cn1:guibuilder -DclassName=com.example.MyForm
- put Core Components Button into the form
- in Properties Inspector switch to Event
- click Action Event -> small x appears to the right -> no visual indication a save is needed
- exit GuiBuilder
- check contents of MyForm.gui file: cat common/src/main/guibuilder/com/example/MyForm.gui -> actionEvent="true" is missing from component "Button"
Open GuiBuilder again start from 5. but this time save before exit. Check the contents of MyForm.gui again -> actionEvent="true" is there.
If in contrast to the above the Text property of the Button is changed there is a visual indication that a save is needed.