[Glade-users] Checking if a window exists

[alef xs4all nl (Alef T Veld)]

I'm trying to check if a window is visible on the screen. This because i'm using one function
for both the main screen buttons and the buttons in the window that displays once one pushes
the buttons on the main screen.

I thought of something like this:

Window w;

        /* Check if the window already exists. If it does, we
        skip this and parse the data, else we realize the widget */
        if((w=GDK_WINDOW_XWINDOW(GTK_WIDGET(app1)->window1))==NULL) {

but it doesn't work. What would be a good way to do this. Also, if one wants to change
the property set in the xml file, for example, Visible=True, how does one change that
in the code?

Many thanks,
Alef