slider display not updated when value is changed by another window

May 4, 2022

I have a window with 2 buttons and a slider.
button1 creates a new window and the button2 changes the slider value of the new window. But slider display not updated when button2 is clicked. What is wrong?

public Window1 newWindow1;
       
public MainWindow()
{
    InitializeComponent();
}

private void Button1_Click(object sender, RoutedEventArgs e)
{
    Window1 newWindow1 = new Window1();
    newWindow1.Show();
    newWindow1.mySlider.Value = 20;
}

private void Button2_Click(object sender, RoutedEventArgs e)
{
     newWindow1.mySlider.Value += 10;
}

>Solution :

In Button1_Click you are creating a local instance of the window instead using the field.

Change your code like this.

private void Button1_Click(object sender, RoutedEventArgs e)
{
    newWindow1 = new Window1();
    newWindow1.Show();
    newWindow1.mySlider.Value = 20;
}

But I hardy recommend following the MVVM pattern when using WPF.