Thread Problem in my window

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WPF

Here is my code

namespace WpfApplication71
{

public partial class MainWindow : Window
{
Thread ProgressThread;
Window w;
public MainWindow()
{
InitializeComponent();
}

private void button1_Click(object sender, RoutedEventArgs e)
{
ProgressThread = new Thread(() =>
{
w = new Window();
RoundProgressBar objprogress=new RoundProgressBar();
w = new Window();
w.Margin = new Thickness(0, 0, 50, 0);
w.WindowState = WindowState.Normal;
w.WindowStartupLocation = WindowStartupLocation.CenterOwner;
w.Height = 80;
w.Width = 80;
w.ResizeMode = ResizeMode.NoResize;
w.AllowsTransparency = true;
w.WindowStyle = WindowStyle.None;
RoundProgressBar Progress = new RoundProgressBar();
w.Content = objprogress;
w.ShowInTaskbar = false;
w.ShowDialog();
w.Content = Progress;
w.ShowInTaskbar = false;
w.ShowDialog();

w.Closed += (sender2, e2) =>
w.Dispatcher.InvokeShutdown();

System.Windows.Threading.Dispatcher.Run();
});

ProgressThread.SetApartmentState(ApartmentState.STA);
ProgressThread.Start();
}



}
}

when i click the button thread start the progress bar in middle of the screen .when i change main screen that progree bar window not changing .

I want to display that progress bar middle of that window . if i move anywhere.

w.Owner = this;

i know with the help of this code this will work perfect.but i am working in thread so this error is occured

"The calling thread cannot access this object because a different thread owns it"

Please help me out from this problem