Making MODEL Invisible Prior to Running Model Callback CloseFcn

I have a model that is doing a lot in its close function. I would like to make the model invisible during this time. So basically the first command I want in the close function is to make the model invisible. Something like set(gcs, 'visible','off').

I see the model has a Handles property which has a visible parameter. But when I get a copy of this I cannot update back into the model because Matalb says it's a read-only property.

Here is what I have tried:

h=get_param(gcs,'handles')
b=get(h)
set(b,'visible','off')
set_param(gcs,'handles',b)

Of course this doesn't work. Basically I still want the model in memory (until the close function completes, of course). I just don't want the user to have the opportunity to click around.

Thanks