How to disable close button from window form using .NET application

How to disable window close button ("X") in .NET VB.NET                         To disable close button from the window form using vb.net needs some Dlls from system library. Call DisableCloseButton(me.Handle) function from your window form button click event or from where you want to disable "x" button. Code-1   Private Const MF_BYPOSITION As Int32 = &H400 Private Const MF_REMOVE As Int32 = &H1000 Private Declare Auto Function GetSystemMenu Lib "user32.dll" (ByVal hWnd As IntPtr, ByVal bRevert As Int32) As IntPtr Private Declare Auto Function GetMenuItemCount Lib "user32.dll" (ByVal hMenu As IntPtr) As Int32 Private Declare Function DrawMenuBar Lib "user32.dll" (ByVal hwnd As IntPtr) As Boolean Private Declare Auto Function RemoveMenu Lib "user32.dll" (ByVal hMenu As IntPtr, ByVal nPosition As Int32, ByVal wFlags As Int32) As Int32 'This method will be used to disable the Form "X" button Public Shared Sub DisableCloseButton(ByVal hwnd As IntPtr) Dim hMenu As IntPtr, n As Int32 hMenu = GetSystemMenu(hwnd, 0) If Not hMenu.Equals(IntPtr.Zero) Then               n = GetMenuItemCount(hMenu)      If n > 0 Then                    RemoveMenu(hMenu, n - 1, MF_BYPOSITION Or MF_REMOVE)          RemoveMenu(hMenu, n - 2, MF_BYPOSITION Or MF_REMOVE)                    DrawMenuBar(hwnd)      End If End If End Sub Code-2 Another way to disable close button from window form , override  "CreateParams" property. You have to Include following code in your in your window form.      Private Const CP_NOCLOSE_BUTTON As Integer = &H200      Protected Overloads Overrides ReadOnly Property CreateParams() As    CreateParams          Get              Dim myCp As CreateParams = MyBase.CreateParams     myCp.ClassStyle = myCp.ClassStyle Or CP_NOCLOSE_BUTTON               Return myCp End Get      End Property C#.NET In C#.net its simple just override "CreateParams" property, that's all. Including following code in your in your window form. private const int CP_NOCLOSE_BUTTON = 0x200; protected override CreateParams CreateParams {    get    {       CreateParams myCp = base.CreateParams;       myCp.ClassStyle = myCp.ClassStyle | CP_NOCLOSE_BUTTON;       return myCp;     }  }