1.窗体置前

3.窗体
     

1.
  执行如下按钮事件
  private void btnFormMax_Click(object sender, EventArgs e)
  {
     if (this.WindowState == FormWindowState.Maximized)
     {
         this.WindowState = FormWindowState.Normal;
     }
     else
     {
         this.WindowState = FormWindowState.Maximized;
     }
  }
  窗体最大化时 非全屏 不会遮盖任务栏
  此时this.FormBorderStyle. 默认为 Sizable

2.
  执行如下按钮事件
  private void btnFormMax_Click(object sender, EventArgs e)
  {
      if (this.WindowState == FormWindowState.Maximized)
      {       
         this.WindowState = FormWindowState.Normal;
      }
      else
      {
         this.FormBorderStyle. = FormBorderStyle.None;
         this.WindowState = FormWindowState.Maximized;
      }
   }

  窗体最大化时 会全屏 及遮盖任务栏
  此时this.FormBorderStyle. 为 None 不会显示窗体标题栏等相关

3.
  执行如下按钮事件
  private void btnFormMax_Click(object sender, EventArgs e)
  {
      if (this.WindowState == FormWindowState.Maximized)
      {       
         this.WindowState = FormWindowState.Normal;
      }
      else
      {
         this.FormBorderStyle. = FormBorderStyle.None;
         this.MaximumSize = new Size(Screen.PrimaryScreen.WorkingArea.Width, Screen.PrimaryScreen.WorkingArea.Height);
         this.WindowState = FormWindowState.Maximized;
      }
   }

  窗体最大化时 非全屏 不会遮盖任务栏
  此时this.FormBorderStyle. 为 None 不会显示窗体标题栏等相关