Question

Possible Duplicate:
Updating One Form After Event Occurs in Another Form

Relevant info: Using WPF Application, C#, Visual Studio 2010, .Net 4

I have two windows: Window1 and MainWindow. In Window1 I have a checkbox, that when checked, will set a label1 in MainWindow to not visible. How would I go about this?

I can’t do MainWindow newWindow = new MainWindow() because I’m not trying to make a new main window. I tried the following code but I get a exception thrown: {“Object reference not set to an instance of an object.”}`.

private void checkBox4_Checked(object sender, RoutedEventArgs e)
{
   if (checkBox4.IsChecked == true)
   {
       (Application.Current.MainWindow as MainWindow).label1.Visibility = 
                   Visibility.Hidden;
   }
   else
   {
       (Application.Current.MainWindow as MainWindow).label1.Visibility = 
                   Visibility.Visible;
   }
}

What would be the best way to go about this? Thanks in advanced.

Answer 1

Add an event to Window1:

public event Action<bool> SomethingChecked; //TODO rename to indicate what was checked

When the checkbox is checked raise that event:

private void checkBox4_Checked(object sender, RoutedEventArgs e)
{
    if(SomethingChecked != null)
        SomethingChecked(checkBox4.IsChecked);
}

Then add an event handler from the main form:

Window1 other = new Window1();
other.SomethingChecked += checked => label1.Visibility = 
    checked ? Visibility.Visible : Visibility.Hidden;