Disable/enable Button

I have this button disabled by default and I want to enable it later, after a CB_LIST_INPUT event.

The button is blocked (Pt_BLOCKED flag is set) by default and I want ot “unblock” it later on the program. Is it possible ? I have look at PtSetResource with PtSetArg(args[x],Pt_ARG_FLAGS, Pt_BLOCKED,…)
but I don’t know how to unset teh flag.

Can it be done like that or is there a better way to achieve the same ?

TIA

LA

PtSetResource(args[x], Pt_ARG_FLAGS, Pt_FALSE, Pt_BLOCKED);

Thanks a lot !