Automatic regeneration when calling sub

Hi all !

I don't quite understand the behaviour of autocad's regeneration
of the drawing.

I have a sub that I call "test". I use it for testing new vba
macros because I always have a toolbar button activating it.

It only contains the code to trigger the sub I am actually working
on, e.g. :
Sub test()
SubCurrentlyInDeveloppement
End Sub

When I work that way, the active viewport is automatically
regenerated after every drawing operation, and that takes a lot of
CPU time out of my macro.
However, when I directly call the SubCurrentlyInDeveloppement in
the toolbar button (that is, without calling it from within
another Sub), the drawing does not regenerate until I call
Thisdrawing.Regen activeviewport.

How is this possible ? I tried to set
ThisDrawing.SetVariable "LAYOUTREGENCTL", 0
ThisDrawing.SetVariable "REGENMODE", 0
in the "test" sub, but it does not change anything !

How can I just disable drawing regeneration while any macro is
running, and until it is over ?

Thanks a lot for helping !

Arnaud