Cancel mouse wheel scrolling in a combobox VB.NET

Marcus J Smith

I am trying to cancel the mouse wheel scrolling in a combobox and I noticed that there is a Combobox.MouseWheel event but that just relays information it doesnt allow me to cancel the event. This is the only thing I have found with some type of definite answer[^] and it looks like something that I dont want to do unless I have to.

CleaKO

"Now, a man would have opened both gates, driven through and not bothered to close either gate." - Marc Clifton (The Lounge)

Dave Kreskowiak

That's the only way you're going to be able to do it. You have to intercept the Scroll Wheel messages before they get processed by the controls WndProc.

A guide to posting questions on CodeProject[^]
Dave Kreskowiak Microsoft MVP Visual Developer - Visual Basic
2006, 2007

Marcus J Smith

Here's what Im trying and it doesnt pick up the scrolling while focused on the combobox only if I scroll with the mousewheel while focused anywhere else does it work. Private Const WM_MOUSEWHEEL As Integer = &H20A Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message) Select Case m.Msg Case WM_MOUSEWHEEL Select Case True Exit Sub End Select MyBase.WndProc(m) End Sub

CleaKO

"Now, a man would have opened both gates, driven through and not bothered to close either gate." - Marc Clifton (The Lounge)

Dave Kreskowiak

Where is this code?? Is it on your Form or is it part of a custom ComboBox control?? This code has to be part of a custom ComboBox to work. You got it mostly right. Though, your Select Case is really messed up. You don't need the Select Case True. That will ALWAYS execute it's code no matter what. All you want is to NOT process MouseWheel messages. All other MUST be passed to the base ComboBox control. Soooo....

Public Class MyComboBox
Inherits ComboBox

Private Const WM\_MOUSEWHEEL As Integer = &H20A

Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
    Select Case m.Msg
        Case WM\_MOUSEWHEEL
            ' If we see a MouseWheel message, do not process it!
            Exit Sub
    End Select

    ' All other messages get processed as normal.
    MyBase.WndProc(m)
End Sub

End Class

... is what you're looking for.

A guide to posting questions on CodeProject[^]
Dave Kreskowiak Microsoft MVP Visual Developer - Visual Basic
2006, 2007

Marcus J Smith

I sure was hoping it was easier but no biggie. Ive dont a few custom controls in my day...:). That select true used to contain code by the way but I was still in the middle of messing with it.

CleaKO

"Now, a man would have opened both gates, driven through and not bothered to close either gate." - Marc Clifton (The Lounge)