void Footer_MouseLeftButtonDown(object sender, MouseButtonEventArgs e) { //get the mouse's current position inside of the Window start = e.GetPosition(Application.Current.MainWindow); //get the current size of the element OriginalWidthandHeight.X = this.ThisControlGrid.ActualWidth; OriginalWidthandHeight.Y = this.ThisControlGrid.ActualHeight; //capture the mouse on the element to indicate that it is in use Footer.CaptureMouse(); }