How to stop a new window to be opened every time? - wpf

Question

I have a WPF application in which on a click of a menu item a window is opened. If the same menu item is clicked again when the window is already open, it is opening a new window but I don't want a new window to be opened every time.
What I need is, if the window is already open, the same window should be focused not a new window.

Answer 1

//First we must create a object of type the new window we want the open.
NewWindowClass newWindow;
private void OpenNewWindow() {
//Check if the window wasn't created yet
if (newWindow == null)
{
//Instantiate the object and call the Open() method
newWindow= new NewWindowClass();
newWindow.Show();
//Add a event handler to set null our window object when it will be closed
newWindow.Closed += new EventHandler(newWindow_Closed);
}
//If the window was created and your window isn't active
//we call the method Activate to call the specific window to front
else if (newWindow != null && !newWindow.IsActive)
{
newWindow.Activate();
}
}
void newWindow_Closed(object sender, EventArgs e)
{
newWindow = null;
}
I think this solve your problem.
Att,

Answer 2

If your opened windows is used as simple dialog box you can use following code
window.ShowDialog();
when the dialog will show you cannot press any menu items unit you close this window

Answer 3

A rather brute force approach like this also works:
bool winTest = false;
foreach (Window w in Application.Current.Windows)
{
if (w is testWindow)
{
winTest = true;
w.Activate();
}
}
if (!winTest)
{
testWindow tw = new testWindow();
tw.Show();
}

Answer 4

You can create a field and check if it's set:
private Window _dialogue = null;
private void MaekWindowButton_Click(object sender, RoutedEventArgs e)
{
if (_dialogue == null)
{
Dialogue diag = new Dialogue();
_dialogue = diag;
diag.Closed += (s,_) => _dialogue = null; //Resets the field on close.
diag.Show();
}
else
{
_dialogue.Activate(); //Focuses window if it exists.
}
}