Restriction about opening multiple window [SOLVED]

I have developped a school management system. In which there is these is a main window consistiing menus on menubar. clicking on Each menubar a new window appears. If I click on several menus then all menus appear simultaneously. I want to provide an warning/error message when someone tries to open multiple window. My question is How can I detect that is there any other window is opened or not (without the main window).
Is there any way of it or something else?


Thanks in advanced.

Maybe the Frame.getFrames() (static) method can be of help.

kind regards,

Jos

Yes,It works.Thanks Jos.

Soprry,It doesn't accomplish my need.
Let A main window is X and sub window are B and C,........
At first Frame.getFrames() returns 1 frame.
when I open B
Frame.getFrames() returns 2 frame.
closing B,again opening,
Frame.getFrames() returns 3 frame.



But I need to know that how many windows are currently opened?Is there any way?