Disabling close [X] button in VB.Net

[DWetherilt]

See subject! Tried the VB6 implementation that I found on the site but get the error "Hwnd is not a member of 'My_Prog_name.MainForm'" when trying to compile for debugging. Any ideas anyone??!?

I'm assuming there's probably a very easy way to do this in VB.net instead of grabbing the forms handle.

[Frans C]

If I remember correctly, the VB6 property Hwnd is called Handle in VB.NET.

[DWetherilt]

Thanks Frans, but I did try that and got a "Value of Type 'System.InPtr' (referring to 'Me.Handle' of course) cannot be converted to Long. This makes sense when you look at the code:

'Declarations

'Paste this into the declaration section:

Declare Function GetSystemMenu Lib "user32" _
(ByVal hwnd As Long, ByVal bRevert As Long) As Long

Declare Function GetMenuItemCount Lib "user32" _
(ByVal hMenu As Long) As Long

Declare Function DrawMenuBar Lib "user32" _
(ByVal hwnd As Long) As Long

Declare Function RemoveMenu Lib "user32" _
(ByVal hMenu As Long, ByVal nPosition As Long, _
ByVal wFlags As Long) As Long
Public Const MF_BYPOSITION = &H400&
Public Const MF_REMOVE = &H1000&
Form Code

'Then paste this into the form:

Private Sub Form_Load()
Dim hSysMenu As Long
Dim nCnt As Long

'First, show the form
Me.Show

'Get handle to our form's system menu
'(Restore, Maximize, Move, close etc.)
hSysMenu = GetSystemMenu(Me.hwnd, False)

If hSysMenu Then
'Get System menu's menu count
nCnt = GetMenuItemCount(hSysMenu)

If nCnt Then

'Menu count is based on 0 (0, 1, 2, 3...)

RemoveMenu hSysMenu, nCnt - 1, _
MF_BYPOSITION Or MF_REMOVE

RemoveMenu hSysMenu, nCnt - 2, _
MF_BYPOSITION Or MF_REMOVE 'Remove the seperator

DrawMenuBar Me.hwnd
'Force caption bar's refresh. Disabling X button

Me.Caption = "Try to close me!"
End If
End If
End Sub



Look at the declarations section. We are calling "user32.dll" to handle the window. I'm sure the .Net framework probably has a more efficient way of doing this.

This is where I'm stuck. I think I'm nearly there but need re-assurance that I'm going the right way about this.

[Cander]

API usage is different between VB6 and .NET you cant just take Vb6 api code and paste into .NET. paremeter types have to be change Long to Integer, Integer to Short, cant use Any, etc. Plus you have to use COM interop. But instead of doing all that, ....

Set the property Form.ControlBox to false.

[DWetherilt]

Getting there. I do understand that you can't just paste VB6 code into VB.net and "it'll work". I used the VB6 code as a means of getting an idea of how it used to be done. As it turns out I don't think any of the code will be of any use to me.

Thanks for the advice Cander but what I need is a little more sophisticated than just dis-abling the controlbox!!

The program still needs to minimize and maximize from the toolbar but it can't close as there will probably be open files if the main process isn't stopped in the correct manner. This is the main reason that I need to handle the close box directly. The other reason is so that I can deploy it to the system tray in later releases when the close button is clicked.

Can anybody provide me with a decent answer??!? There must be some-one with the knowledge!!

[Frans C]

OK, I'm sure there must be a .NET way to do it, but here is your code converted as it was.

In a module:

Declare Function GetSystemMenu Lib "user32" _
(ByVal hwnd As IntPtr, ByVal bRevert As Integer) As IntPtr
 
    Declare Function GetMenuItemCount Lib "user32" _
    (ByVal hMenu As IntPtr) As Integer
 
    Declare Function DrawMenuBar Lib "user32" _
    (ByVal hwnd As IntPtr) As Integer
 
    Declare Function RemoveMenu Lib "user32" _
    (ByVal hMenu As IntPtr, ByVal nPosition As Integer, _
    ByVal wFlags As Integer) As Integer
    Public Const MF_BYPOSITION As Integer = &H400
    Public Const MF_REMOVE As Integer = &H1000

In your form (I used form2):

Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim hSysMenu As IntPtr
        Dim nCnt As Long
 
        'First, show the form 
        Me.Show()
 
        'Get handle to our form's system menu 
        '(Restore, Maximize, Move, close etc.) 
        hSysMenu = GetSystemMenu(Me.Handle, 0)
 
        If Not hSysMenu.Equals(0) Then
            'Get System menu's menu count 
            nCnt = GetMenuItemCount(hSysMenu)
 
            If nCnt Then
 
                'Menu count is based on 0 (0, 1, 2, 3...) 
 
                RemoveMenu(hSysMenu, nCnt - 1, _
                MF_BYPOSITION Or MF_REMOVE)
 
                RemoveMenu(hSysMenu, nCnt - 2, _
                MF_BYPOSITION Or MF_REMOVE) 'Remove the seperator 
 
                DrawMenuBar(Me.Handle)
                'Force caption bar's refresh. Disabling X button 
 
                Me.Text = "Try to close me!"
            End If
        End If
 
    End Sub

[ddrees]

Originally posted by DWetherilt
The program still needs to minimize and maximize from the toolbar but it can't close as there will probably be open files if the main process isn't stopped in the correct manner. This is the main reason that I need to handle the close box directly.

I'm still a little new at this , so I apologize in advance if I am misunderstanding your situation, but I know that if the user closes a form using the X button, you can catch the event, and even cancel it, if you want. So another way to solve your problem may be to catch that event and write code that makes sure that the process is stopped correctly before closing the program.

I saw some sample code somewhere (I can try to find it again, if you would like) that showed how to catch a close event and determine where it came from (closing the form by hitting the close button, closing the parent form, using the form menu, etc.). The point of the sample code that I saw was to handle the scenario when the user clicked the close [X] button. If anyone wants to see the code, let me know I'll try to find it and post it here.

[Magiaus]

http://www.vbforums.com/showthread.p...hreadid=159297

that link is to a thread where i talk to myself about adding a menu item to a forms system menu not it's menu bar it's system menu

after rereading that damn i sound like a jerk

[DWetherilt]

Frans. Thanks for doing that conversion - it seems blatently obvious now!!! It worked a treat!! Hope I can help you one day.