Imports System.Windows.Forms
Imports System.Runtime.InteropServicesPublic Class CustomFormInherits Form' P/Invoke constantsPrivate Const WM_SYSCOMMAND As Integer = &H112Private Const MF_STRING As Integer = &H0Private Const MF_SEPARATOR As Integer = &H800' P/Invoke declarations<DllImport("user32.dll", CharSet:=CharSet.Auto, SetLastError:=True)>Private Shared Function GetSystemMenu(hWnd As IntPtr, bRevert As Boolean) As IntPtrEnd Function<DllImport("user32.dll", CharSet:=CharSet.Auto, SetLastError:=True)>Private Shared Function AppendMenu(hMenu As IntPtr, uFlags As Integer, uIDNewItem As Integer, lpNewItem As String) As BooleanEnd Function<DllImport("user32.dll", CharSet:=CharSet.Auto, SetLastError:=True)>Private Shared Function InsertMenu(hMenu As IntPtr, uPosition As Integer, uFlags As Integer, uIDNewItem As Integer, lpNewItem As String) As BooleanEnd Function' ID for the About item on the system menuPrivate SYSMENU_ABOUT_ID As Integer = &H1Public Sub New()End SubProtected Overrides Sub OnHandleCreated(e As EventArgs)MyBase.OnHandleCreated(e)' Get a handle to a copy of this form's system (window) menuDim hSysMenu As IntPtr = GetSystemMenu(Me.Handle, False)' Add a separatorAppendMenu(hSysMenu, MF_SEPARATOR, 0, String.Empty)' Add the About menu itemAppendMenu(hSysMenu, MF_STRING, SYSMENU_ABOUT_ID, "&About…")End SubProtected Overrides Sub WndProc(ByRef m As Message)MyBase.WndProc(m)' Test if the About item was selected from the system menuIf m.Msg = WM_SYSCOMMAND AndAlso m.WParam.ToInt32 = SYSMENU_ABOUT_ID ThenMessageBox.Show("Custom About Dialog")End IfEnd Sub
End Class