How to prevent JInternalFrame from running more than one instance?

I have one JDesktopPane with two JInternalFrame inside. How can i identify if a particular instance of JInterframe is running? thanks in advance!
[152 byte] By [paoa] at [2007-11-26 18:52:33]
# 1
What do you mean by instance is running?If you have the JInternalFrame object you can just check if it's visible:JInternalFrame.isVisible
Rodney_McKaya at 2007-7-9 6:26:36 > top of Java-index,Desktop,Core GUI APIs...