The VBA and VB6 Add-In Object Models (VBIDE) expose a CommandBarEvents object that have a Click event, and the event signature is:
Dim WithEvents CmdBarEvents As CommandBarEvents Private Sub CmdBarEvents_Click(ByVal CommandBarControl As Object, handled As Boolean, CancelDefault As Boolean)
And a reference to a CommandBarControl is passed to VBE.Events.CommandBarEvents to register the event handler for that CommaneBarControl:
Set CmdBarEvents = Application.VBE.Events.CommandBarEvents(CmdBarItem)
The Office object model defines individual CommandBar controls that have their own Click events, for example, the CommandBarControl object which has a Click event, and the signature is:
Dim WithEvents CmdBarBtn As CommandBarButton Private Sub CmdBarBtn_Click(ByVal Ctrl As Office.CommandBarButton, CancelDefault As Boolean)
And a reference to a CommandBarButton is assigned to the WithEvents object:
Set CmdBarButton = myButton
Why is there a difference, and which should I prefer?
I'm attaching events to the controls on the VBE's CommandBars (as opposed to CommandBars within the host application).
Office CommandBars don't have access to a CommandBarEvents object, so I assume that they must use the CommandBarButton.Click event. But the VBE (under any Office Host) has access to CommandBarButton events AND CommandBarEvents events, so I could use either approach, although the mere presence of the CommandBarEvents object suggests that it is the preferred method (and probably the only method in non-Office VBA hosts), and most of the online examples of adding event handlers to VBE CommandBars do use CommandBarEvents.
Carlos Quintero of MZ Tools has wonderously useful, but in this case, mildly contradictory information on his site. He suggests that The CommandBarEvents approach was used in the old Microsoft Visual Basic 5.0 / 6.0 environment, but also uses the CommandBarControl.Click approach on this page
Is there something special about the VBE and attaching events to CommandBar controls? Are there any problems (memory leaks, IDTExtensibility2 shutdown problems and the like) if I choose to use the CommandBarControl events over the CommandBarEvents events?
VB6, being an IDE from 1998 (and VB5 from 1997) must use always CommandBarEvents. The Office commandbars that they use are borrowed from Office 97, whose CommandBarButton lacked the Click event.
Office 2000 introduced the Click event in the CommandBarButton class, and must be used always for a VBA add-in targeting Office 2000 and higher (or other VBA hosts), because although CommandBarEvents is apparently available, Office 2010 64-bit doesn't support CommandBarEvents (it crashes if used).
Visual Studio is another animal with its own singularities.