Programatically opening a child window when a response window is open

Hi everyone,

I've got a strange problem with my application. I've got a listening thread which waits for a tcp notification and when it receives it, it passes it to the main window which opens a child notification window. This all seems to work pretty well, but I'm having issues when there is a response window already open. I thought that an open response window might stop my notification window from opening, but it doesn't seem to.

If I close the response window then click the close icon on my notification window the notification window closes properly. The problem I have is if, while the response window has focus, the user clicks on the close icon of the notification window, the notification window never closes. It doesn't look like the clicks are registering on the notification window when the response window is open, but once the response window is closed and the user clicks the notification window close icon again, the window won't close. I've checked and Close looks like it is definitely being called, and it even returns 1, but the window stays open and I have to kill the process.

Has anyone seen this issue before? Is it possible to tell if there is a response window open in my application and if so, not to open the notification window?

Thanks.