Direct access to object properties from another window without creating a new window

Question

Hi
First and foremost, I apologize for my grammatical errors; my first language is Persian (Iran).

In my project (WPF) i have many windows. in window form i have no problem to access object property from Another window With following codes for example:

(Application.OpenForms[1].Controls[0].Controls[0].Controls[2] as TreeView).SelectedImageIndex = 10;

But in WPF i try many codes like

Application.Current.MainWindow

Or

App.Current.MainWindow

But the problem was not solved
Please answer accurately by C# coding

My control name is "File" (as menuItem) and i want change header property

Thanks

Answer 1

I found it ,
var window = Application.Current.MainWindow;
(window as MainWindow).File.Header = "my change";

Answer 2

I will show you a sample of updating MainWindow's MenuItem which named myEdit in Window1:
Here is the code for MainWindow.xaml:

<StackPanel>  
        <Menu>  
            <MenuItem Name="myEdit" Header="_Edit" x:FieldModifier="public" >  
                <MenuItem Command="ApplicationCommands.Copy"/>  
                <MenuItem Command="ApplicationCommands.Cut"/>  
                <MenuItem Command="ApplicationCommands.Paste"/>  
            </MenuItem>  
        </Menu>  
        <Button Width="120" Height="30" Content="Show Window1" Click="Button_Click"></Button>  
    </StackPanel>  

MainWindow.xaml.cs is:

 private void Button_Click(object sender, RoutedEventArgs e)  
        {  
            Window1 window1 = new Window1();  
            window1.Show();  
        }  

Create a Button in Window1, and it's click event code is:

 private void Button_Click(object sender, RoutedEventArgs e)  
        {  
            foreach (Window window in Application.Current.Windows)  
            {  
                if (window.GetType() == typeof(MainWindow))  
                {  
                    (window as MainWindow).myEdit.Header = "I changed it from another window1";  
                }  
            }  
        }  

The result picture is:

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