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Path: utzoo!linus!philabs!cmcl2!seismo!lll-crg!well!bmug
From: bmug@well.UUCP (Frederick A. Huxham)
Newsgroups: net.micro.mac
Subject: Re: Is My Thumb an Indicator?
Message-ID: <277@well.UUCP>
Date: Thu, 14-Nov-85 13:16:21 EST
Article-I.D.: well.277
Posted: Thu Nov 14 13:16:21 1985
Date-Received: Fri, 15-Nov-85 20:47:52 EST
References: <1283@wanginst.UUCP> <1318@wanginst.UUCP>
Reply-To: bmug@well.UUCP (Frederick A. Huxham)
Distribution: net
Organization: Whole Earth 'Lectronic Link, Sausalito, CA
Lines: 40

In article <1318@wanginst.UUCP> vishniac@wanginst.UUCP (Ephraim Vishniac) writes:
>> 
>> My problem: when I mouse down in the scrolling or paging regions of my
>> scrollbar, my action proc is called exactly as advertised with the
>> appropriate handle and part code on the stack.  When I mouse down in the
>> thumb (the little square item that shows the scroll bar position), my
>> action proc is called without parms as though the thumb were an indicator!
>
>Since writing this, I've found that the Control Manager chapter does mention
>that the thumb of a scroll bar is, generically speaking, the "indicator" of
>a "dial."  This still fails to explain, though, why my actionProc is called
>with varying argument lists and how one is expected to deal with this.  So,
>I repeat my original question:
>
>> Has anyone run into this curiosity?  Has anyone used a scrollbar action
>> proc and *not* run into this?
>-- 
>Ephraim Vishniac
>  [apollo, bbncca, cadmus, decvax, harvard, linus, masscomp]!wanginst!vishniac
>  vishniac%Wang-Inst@Csnet-Relay


On page 20 of the Control Manager (phone book edition) it says:

	"- If actionProc is NIL, TrackControl performs no additional actions.
	   This is appropriate for simple buttons, check boxes, radio
	   buttons, and the THUMB OF A SCROLL BAR."

You shouldn't need to call an actionProc for a mouseDown in the thumb of
a scroll bar unless your scroll bar does some very weird things.

My last response to this query showed how to handle scroll bar mouseDowns.

If your scroll bar (thumb) has to exhibit strange behavior, what is it that 
its supposed to do.  

Fred A. Huxham