In some situation during your project you did not need or want the close button of your form. This article is about how you can disable the close button of your form using the window API’s.


Steps you will do
Start visual studio and create a new window application.
Drop two button controls on the form.
Set the properties of the First as below:
Name = btnDisable, Text = Disable Close Button



Set the properties of the Second as below:
Name = btnClose, Text = Close Me



Drop a label control on your form and set its Text property as below:
Text = It is very simple to disable the close button of form.



Declare the following functions:
Private Declare Function RemoveMenu Lib "user32" (ByVal hMenu As IntPtr, ByVal nPosition As Integer, ByVal wFlags As Long) As IntPtr



Private Declare Function GetSystemMenu Lib "user32" (ByVal hWnd As IntPtr, ByVal bRevert As Boolean) As IntPtr



Private Declare Function GetMenuItemCount Lib "user32" (ByVal hMenu As IntPtr) As Integer



Private Declare Function DrawMenuBar Lib "user32" (ByVal hwnd As IntPtr) As Boolean



Private Const MF_BYPOSITION = &H400

Private Const MF_REMOVE = &H1000

Private Const MF_DISABLED = &H2



Now write the following function which will disable the close button of your form.
Public Sub DisableCloseButton(ByVal hwnd As IntPtr)



Dim hMenu As IntPtr

Dim menuItemCount As Integer



hMenu = GetSystemMenu(hwnd, False)

menuItemCount = GetMenuItemCount(hMenu)



Call RemoveMenu(hMenu, menuItemCount - 1, _



MF_DISABLED Or MF_BYPOSITION)

Call RemoveMenu(hMenu, menuItemCount - 2, _



MF_DISABLED Or MF_BYPOSITION)

Call DrawMenuBar(hwnd)



End Sub



In the click event of “btnClose” write the code to exit from application as below:
'To exit from the application

Application.Exit()



· In the click event of “btnDisable” write call the “DisableCloseButton” function to disable the close button as below:



'To call the function by passing the handler of form

DisableCloseButton(Me.Handle)