Probably a little thing, but made me wonder for a while.
In NetBeans 7.0.1 swing designer when you set an Action for a component using Set Action menu option when you right click on the component in designer, after you reload the project in IDE the text caption on the component disappears.
This happens because when you set up an action new separate entry gets created in properties file for a text that is going to be shown on the control.
In the Set action dialog there is a Text property which you can specify. It's going to be shown on a component.