using System;using System.Windows.Forms;using System.Drawing;namespace CSImageFullScreenSlideShow{ public class FullScreen {  private FormWindowState winState;  private FormBorderStyle brdStyle;  private bool topMost;  private Rectangle bounds;  public FullScreen()  {   IsFullScreen = false;  }  public bool IsFullScreen  {   get;   set;  }  public void EnterFullScreen(Form targetForm)  {   if (!IsFullScreen)   {    Save(targetForm); // Save the original form state.    targetForm.WindowState = FormWindowState.Maximized;    targetForm.FormBorderStyle = FormBorderStyle.None;    targetForm.TopMost = true;    targetForm.Bounds = Screen.GetBounds(targetForm);    IsFullScreen = true;   }  }  /// <summary>  /// Save the current Window state.  /// </summary>  private void Save(Form targetForm)  {   winState = targetForm.WindowState;   brdStyle = targetForm.FormBorderStyle;   topMost = targetForm.TopMost;   bounds = targetForm.Bounds;  }  /// <summary>  /// Leave the full screen mode and restore the original window state.  /// </summary>  public void LeaveFullScreen(Form targetForm)  {   if (IsFullScreen)   {    // Restore the original Window state.    targetForm.WindowState = winState;    targetForm.FormBorderStyle = brdStyle;    targetForm.TopMost = topMost;    targetForm.Bounds = bounds;    IsFullScreen = false;   }  } }}

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Text;using System.Windows.Forms;namespace CSImageFullScreenSlideShow{ public partial class Test : Form {  public Test()  {   InitializeComponent();   }  private FullScreen fullScreen = new FullScreen();  private void button1_Click(object sender, EventArgs e)  {   if (fullScreen.IsFullScreen)   {    fullScreen.LeaveFullScreen(this);   }   else   {    fullScreen.EnterFullScreen(this);   }  } }}