Why we need a Java glass pane?

Question

Why we need a Java glass pane,
I think the Layered and the Content Pane with the Menu Bar are enough Panes to work with a Frame container.

I know that the glass Pane is hiden and that it can intercept input events for the root Pane, but the Content Pane is the same I think, so for what its usefull?

Thanks in advance :)

Answer 1

Content pane excludes the menu bar, glass pane does not. AND, and much more important, the class pane is not meant to contain elements but to function as a decoration of the overall composition of panes, layers, and so on:

http://docs.oracle.com/javase/tutorial/uiswing/components/rootpane.html#glasspane