#region Using directives

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;

#endregion

namespace SingleMDISample {
  partial class MDIParentForm : Form {

    [DllImport("user32.dll")]
    static extern bool SetForegroundWindow(IntPtr hWnd);

    public MDIParentForm() {
      InitializeComponent();
    }

    static public int FormCount = 0;

    public void CreateMDIChildWindow(string fileName) {

      // This is necessary to bring the MDI parent window to the front,
      // since Activate and BringToFront don't seem to have any effect.
      SetForegroundWindow(this.Handle);
      
      // Detect if file is already open
      if( !string.IsNullOrEmpty(fileName) ) {
        foreach( MDIChildForm openForm in this.MdiChildren ) {
          if( string.Compare(openForm.FileName, fileName, true) == 0 ) {
            openForm.Activate();
            return;
          }
        }
      }

      // If file not open, open it
      MDIChildForm form = new MDIChildForm();
      form.OpenFile(fileName);
      form.MdiParent = this;
      form.Show();
    }

    private void newToolStripMenuItem_Click(object sender, EventArgs e) {
      this.CreateMDIChildWindow(null);
    }

    private void openToolStripMenuItem_Click(object sender, EventArgs e) {
      if( this.openFileDialog.ShowDialog() == DialogResult.OK ) {
        this.CreateMDIChildWindow(this.openFileDialog.FileName);
      }
    }
  }
}