I've managed to create a Class that allows me to add an 'About...' button to the System Menu of any form. This part works fine, with the button being added by the load
event of the form, but how do I handle clicks of that button? Thanks.
Here is how I'm adding the button -
Private Sub mainForm_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
{More code....}
Dim SysMenu = New SystemMenu(Me)
{More code....}
End Sub
And here is the SystemMenu
class -
Imports System.Windows.Forms
Public Class SystemMenu
Private Declare Function GetSystemMenu Lib "user32" (ByVal hWnd As IntPtr, ByVal bRevert As Boolean) As IntPtr
Private Declare Function AppendMenu Lib "user32" Alias "AppendMenuA" (ByVal hMenu As IntPtr, ByVal uFlags As Int32, ByVal uIDNewItem As IntPtr, ByVal lpNewItem As String) As Boolean
Private Const MF_STRING As Integer = &H0
Private Const MF_SEPARATOR As Integer = &H800
Private m_hSysMenu As IntPtr
Private Property hSysMenu() As IntPtr
Get
Return Me.m_hSysMenu
End Get
Set(ByVal Value As IntPtr)
Me.m_hSysMenu = Value
End Set
End Property
'**
' Constructor
'*
Protected Friend Sub New(ByRef Form As Form)
Me.hSysMenu = GetSystemMenu(Form.Handle, False)
AddAbout(Form)
End Sub
'**
' Add an 'About' button to the system menu of the given form
'*
Private Sub AddAbout(ByRef Form As Form)
AppendMenu(Me.hSysMenu, MF_SEPARATOR, 1000, Nothing)
AppendMenu(Me.hSysMenu, MF_STRING, 1001, "About...")
End Sub
End Class
Check this out. Add the SubclassedSystemMenu.vb
file to the project and add this to your main form
Private WithEvents sysMenu As SubclassedSystemMenu
Protected Overrides Sub OnLoad(e As System.EventArgs)
sysMenu = New SubclassedSystemMenu(Me.Handle.ToInt32, "&About...")
End Sub
And then subscribe to its LaunchDialog
event and open the form
Private Sub sysMenu_LaunchDialog() Handles sysMenu.LaunchDialog
Dim f as New frmAbout
f.ShowDialog(Me)
End Sub
And here is the SubclassedSystemMenu
class
Public Class SubclassedSystemMenu
Inherits System.Windows.Forms.NativeWindow
Implements IDisposable
Private Declare Function GetSystemMenu Lib "user32" (ByVal hwnd As Int32, _
ByVal bRevert As Boolean) As Int32
Private Declare Function AppendMenu Lib "user32" Alias "AppendMenuA" (ByVal hMenu As Int32, _
ByVal wFlags As Int32, _
ByVal wIDNewItem As Int32, _
ByVal lpNewItem As String) As Int32
Private Const MF_STRING As Int32 = &H0 ' Menu string format
Private Const MF_SEPARATOR As Int32 = &H800 ' Menu separator
Private Const WM_SYSCOMMAND As Int32 = &H112 ' System menu
Private Const ID_ABOUT As Int32 = 1000 ' Our ID for the new menu item
Private mintSystemMenu As Int32 = 0 ' Parent system menu handle
Private mintHandle As Int32 = 0 ' Local parent window handle
Private mstrMenuItemText As String = String.Empty ' New menu item text
Public Event LaunchDialog()
Public Sub New(ByVal intWindowHandle As Int32, _
ByVal strMenuItemText As String)
Me.AssignHandle(New IntPtr(intWindowHandle))
mintHandle = intWindowHandle
mstrMenuItemText = strMenuItemText
' Retrieve the system menu handle
mintSystemMenu = GetSystemMenu(mintHandle, 0)
If AddNewSystemMenuItem() = False Then
Throw New Exception("Unable to add new system menu items")
End If
End Sub
Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
Select Case m.Msg
Case WM_SYSCOMMAND
MyBase.WndProc(m)
If m.WParam.ToInt32 = ID_ABOUT Then
If mintSystemMenu <> 0 Then
RaiseEvent LaunchDialog()
End If
End If
Case Else
MyBase.WndProc(m)
End Select
End Sub
Public Sub Dispose() Implements System.IDisposable.Dispose
If Not Me.Handle.Equals(IntPtr.Zero) Then
Me.ReleaseHandle()
End If
End Sub
Private Function AddNewSystemMenuItem() As Boolean
Try
' Append the extra system menu items
Return AppendToSystemMenu(mintSystemMenu, mstrMenuItemText)
Catch ex As Exception
Return False
End Try
End Function
Private Function AppendToSystemMenu(ByVal intHandle As Int32, _
ByVal strText As String) As Boolean
Try
' Add the seperator menu item
Dim intRet As Int32 = AppendMenu(intHandle, MF_SEPARATOR, 0, String.Empty)
' Add the About... menu item
intRet = AppendMenu(intHandle, MF_STRING, ID_ABOUT, strText)
If intRet = 1 Then
Return True
Else
Return False
End If
Catch ex As Exception
Return False
End Try
End Function
End Class