HandyControl/Net40/HandyControlDemo_Net40/ViewModel/Controls/WindowDemoViewModel.cs

using System.Windows;
using GalaSoft.MvvmLight.Command;
using HandyControlDemo.Tools;

namespace HandyControlDemo.ViewModel
{
    public class WindowDemoViewModel
    {
        private RelayCommand<string> _openWindowCmd;

        public RelayCommand<string> OpenWindowCmd =>
            _openWindowCmd ?? (_openWindowCmd = new RelayCommand<string>(OpenWindow));

        private void OpenWindow(string windowTag)
        {
            if (AssemblyHelper.CreateInternalInstance($"Window.{windowTag}") is System.Windows.Window window)
            {
                window.Owner = Application.Current.MainWindow;
                window.ShowDialog();
            }
        }
    }
}