Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!cbmvax!ken
From: ken@cbmvax.commodore.com (Ken Farinsky - CATS)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: Boolean Gadget Mutual Exclusion?
Message-ID: <18447@cbmvax.commodore.com>
Date: 1 Feb 91 20:31:58 GMT
References: <659@esosun.UUCP> <18431@cbmvax.commodore.com>
Reply-To: ken@cbmvax.commodore.com (Ken Farinsky - CATS)
Organization: Commodore, West Chester, PA
Lines: 52

In article <18431@cbmvax.commodore.com> ken@cbmvax.commodore.com (Ken Farinsky - CATS) writes:
>>The RKM says that you must use
>>hit-select rather than toggle-select, and GADGIMMEDIATE
>>rather than RELVERIFY when doing mutual exclusion with
>>boolean gadgets.
>
>Mutual exclude gadgets are not supported through Intuition, you have to
>use Gadtools or roll your own.  If you create your own, then you can
>make up the rules as you go along.  The RKM shows one way to implement
>this function.  If you want a different functionality to your gadgets,
>feel free to do so.
>
>The wording in the RKMs is a bit strong, clearly (as long as you follow
>the rules) you can use any technique you want to get the desired result.
>The "code police" will not come to get you if you use another technique.

Ok, I have now talked to the new "Intuition Guru" (Peter Cherna), who
informs me that my answer was not quite correct.  Peter, jump right in
if I miss anything here.

GADGIMMEDIATE is specified as "required" due to problems with removing
gadgets.  When you create mutual exclude gadgets, your code has to spend
a lot of time removing the gadgets, updating the state and refreshing
the display.  The problem is, under 1.3 at least, removing an active
gadget can cause problems with intuition.  If you use RELVERIFY, then
the user can "hold down" the gadget, leaving it active for an extended
period of time.  This might be a problem if the user clicks on the gadget
twice quickly, holding it down the second time.  In this case, the code
might try to remove the gadget (acting on the first message) while the
gadget is active (the user is still holding it down.)  Using GADGIMMEDIATE
solves this problem, as the gadget does not have the extended active
period.

We could not come up with a definitive answer as to why hit-select
gadgets were important, and it may be possible to create the behavior
you want using toggle-select gadgets.  Hit-select gadgets turn out
to be simpler to use, as you know their state after they have been
selected.  You can probably create the desired actions by slightly
modifying the recommended model, rather than trying to re-invent the
wheel.  If you follow the information in the RKMs, you will minimize the
time you spend solving problems that have been encountered in the past.

A lot of expertise has gone into the RKMs.  We'll try to do a better
job of documenting the reasoning behind the information in the next
set.  No, I do not have any information on the timing or the price
of the next set of RKMs, but we are always working to improve the
support we provide to developers.
-- 
--
Ken Farinsky - CATS - (215) 431-9421 - Commodore Business Machines
uucp: ken@cbmvax.commodore.com   or  ...{uunet,rutgers}!cbmvax!ken
bix:  kfarinsky