Prevent multiple instances of windows

Question

How could I prevent opening multiple windows from a wpf application?

I need to open a window from the menu and if I click to open it again, I want the already opened window to become active.

Any suggestions?

Answer 1

You could use the Application.Current.Windows collection for that. Just check whether this collection contains the window you are about to open and if it does, activate it, otherwise create new window and show it:

var existingWindow = Application.Current.Windows.Cast<Window>().SingleOrDefault(w => /* return "true" if 'w' is the window your are about to open */);

if (existingWindow != null) {
    existingWindow.Activate();
}
else {
    // Create and show new window
}