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From: bmug@well.UUCP (Frederick A. Huxham)
Newsgroups: net.micro.mac
Subject: Re: Is My Thumb an Indicator?
Message-ID: <272@well.UUCP>
Date: Sun, 10-Nov-85 16:22:04 EST
Article-I.D.: well.272
Posted: Sun Nov 10 16:22:04 1985
Date-Received: Tue, 12-Nov-85 03:48:09 EST
References: <1283@wanginst.UUCP>
Reply-To: bmug@well.UUCP (Frederick A. Huxham)
Distribution: net
Organization: Whole Earth 'Lectronic Link, Sausalito, CA
Lines: 30

In article <1283@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 parameters as though the thumb were an indicator!
>Since I'm writing in assembler, I can deal with this, but I'd still like
>to know what's going on here.  I'd be in serious trouble if I were using
>a compiled language and couldn't muck with the stack.
>


You don't need to have an action procedure for a mouse-down in the thumb
of a scroll bar, only the arrows or paging regions.  

Typically I do something like the following:

	if(partcode == inThumb) {
		call TrackContr with NIL for an actionProc
	} else if(partcode != 0) {  /* ie. not inThumb */
		call TrackControl with an actionProc
	}


Simply check to see whick part of the scroll bar the user has clicked in
and then call TrackControl with a NIL actionProc if the partcode is inThumb.

Hope this helps,
Fred A. Huxham