I'm working on an owner-drawn combo box which has extended
functionality.  I have to do something to the dropdown list when it
drops down, then undo it when it is closed up again.  But I can't see
an event which seems to be a "CloseUp" event - is there such an event?
Surely there must be!

Steve Marshall wrote:
..NET 2.0: DropDownClosed
Earlier: Override the WndProc message and watch for message
CB_SHOWDROPDOWN (this same message is sent on both drop and close, so it
only means 'close' when it's sent while the dropdown is dropped down).

Show quote Hide quote CB_SHOWDROPDOWN is not a notification message. It's used to drop down the
list programatically. To know when the list closes up you should use the
CBN_CLOSEUP notification. Here's the code for that:

Public Class ComboBoxEx
Inherits ComboBox
    Private Const WM_USER As Integer = &H400
    Private Const WM_COMMAND As Integer = &H111
    Private Const OCM__BASE As Integer = WM_USER + &H1C00
    Private Const OCM_COMMAND As Integer = OCM__BASE + WM_COMMAND

    Private Function HIWORD(ByVal value As Integer) As Short
        Return CShort(New System.Drawing.Point(value).Y)
    End Function

    Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
        If m.Msg = OCM_COMMAND Then
            Dim code As Integer = HIWORD(m.WParam.ToInt32)
            If code = CBN_CLOSEUP Then
                OnCloseUp(EventArgs.Empty)
            End If
        End If
        MyBase.WndProc(m)
    End Sub

    Protected Overridable Sub OnCloseUp(ByVal e As System.EventArgs)
        RaiseEvent CloseUp(Me, e)
    End Sub

    Public Event CloseUp As EventHandler
End Class



   /claes

Many thanks Claes.  I had tried what Larry suggested, but my WndProc
override routine never saw the CB_SHOWDROPDOWN message, so I was about
to post a further question about it.  Your contribution is perfectly
timed!

Claes Bergefall wrote:
Show quoteHide quoteThat's what I deserve for skimming API docs too quickly, I suppose.
Thanks for sorting me out.

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