Tip 197: Preventing a Right-Click from Displaying a Context Menu

December 5, 1995

Abstract
This article explains how to prevent the context menu from appearing when
the user of your Microsoft® Visual Basic® application uses the right mouse
button to click a Text Box control.

Using Message Blaster to Ignore Right-Clicks
A unique feature provided in the Microsoft® Windows® 95 operating system
is its ability to display a context menu for specific controls when you
click with the right mouse button (right-click) over a control. When
developing a Microsoft Visual Basic® application, however, you may not
want this context menu to appear.

Each time you right-click, the system receives a WM_RBUTTONDOWN message.
Using a third-party custom control such as Message Blaster, you can tell
the operating system to ignore this WM_RBUTTONDOWN message.

In the example program below, you want to ignore all right-clicks for the
Text Box control. To accomplish this, you supply Message Blaster with the
handle of the Text Box control and the message you want to trap.

If a right-click is detected while the program is running, the Message
Blaster custom control fools the operating system into believing that
no such action was received. Message Blaster is used to send an EATMESSAGE
message to the operating system. This, in effect, prevents the context
menu from appearing.

Example Program
This program shows how to prevent the context menu from appearing when you
right-click on a Text Box control.

 1. Create a new project in Visual Basic. Form1 is created by default.
 2. Add the following code to the General Declarations section of Form1:

Const EATMESSAGE = 0
Const WM_RBUTTONDOWN = &H204

 3. Add the following code to the Form_Load event for Form1:

Private Sub Form_Load()
    MsgBlaster1.hWndTarget = Text1.hWnd
    MsgBlaster1.AddMessage WM_RBUTTONDOWN, POSTPROCESS
End Sub

 4. Add a Text Box control to Form1. Text1 is created by default.
 5. Add a Message Blaster custom control to Form1. MsgBlaster1 is
    created by default.
 6. Add the following code to the MsgBlaster1_Message event:

Private Sub MsgBlaster1_Message(ByVal hWnd As Long, ByVal Msg As Long,
   wParam As Long, lParam As Long, nPassage As Integer, lReturnValue As
Long)
    Select Case Msg
    Case WM_RBUTTONDOWN
        'MsgBox "right mouse was clicked on text box"
        nPassage = EATMESSAGE
    End Select
End Sub

Run the example program by pressing F5. While typing text in the Text Box
control, click the right mouse button. The context menu does not appear
on the screen.