How to do it in MacOS (about ContextualMenu)

I need help to do something in Mac that I do in Windows.
This is the procedure:

In Windows:

  1. I press the right mouse button.
  2. In the MouseDown event I return True, so I can use MouseDrag and MouseUp
  3. If I use MouseDrag I set a flag, otherwise there is no flag.
  4. At MouseUp event ConstructContextualMenu is called automatically, but according to the flag I return True or False, so ContextualMenu is shown or not.

In MacOS:

  1. I press the right mouse button.
  2. Instantly ConstructContextualMenu is called. But at this moment I don’t know yet if MouseDrag will be used. So I can not decide if ContextualMenu must be shown or not.

How should I proceed to do the same in Mac as I do in Windows?

Thanks for your help.

I dont use constructcontextualmenu

Instead I check keyboard.asynccontrolkey in the mousedown/mouseup events which seems to work fine to indicate if it is a right-mousebutton situation

Here (for both platforms):
MouseDown and MouseUp: not used

Code in:
ConstructContextualMenu
ContextulMenuAction

Works fine. I suppose I followed LR examples.

This is in a Listbox.

Edit: typos and additions below:
http://documentation.xojo.com/api/deprecated/rectcontrol.html#rectcontrol-constructcontextualmenu
http://documentation.xojo.com/api/deprecated/rectcontrol.html#rectcontrol-contextualmenuaction

Mac: since MouseDown fires before ConstructContextualMenu, I sometimes use it to build and resolve contextual menus.
Some appropriate #pragma to trap Mac and/or Windows behavior may come useful.

Function MouseDown(X As Integer, Y As Integer) As Boolean if IsContextualClick then //build and resolve contextual menu end if End Function

Thanks to all.
With all these suggestions I think I can do what I pretend.