IS this allright + how to see if it exist

[Nazgul]

I am not able to understand you clearly..
you open a widget on a button click on main window and should be able to close it and open it again ..thats what you wanted to do ..correct me if i am wrong..

You click at the button, it opens/creates/shows the dialog, but if it exist it does nothing.

In the dialog I want when it get destroyed, is that the right message?, it becomes hidden and not destryoed.