This is can be used for many type of controls, mainly for textbox, to make the user unable to open the right click popup menu.
User will need only an extra Timer control for this. No need for SendMessage, Hooking or any other API.

Put a Timer control in the Form, disable it, set its interval to 222.
You can try the interval with different values.

Remember, using this code you can not completely disable the popup menu, but code can work for the time interval you set (in the timer) after the end user presses the right mouse button.

Declarations:
Dim TBox As Control

Code:
Private Sub Text1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
    If Button = 2 Then
        Text1.Enabled = False
        Set TBox = Text1
        Timer1.Enabled = True
    End If
End Sub

Private Sub Timer1_Timer()
    TBox.Enabled = True
    TBox.SetFocus
    Timer1.Enabled = False
End Sub