Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/5/84; site wanginst.UUCP Path: utzoo!linus!wanginst!vishniac From: vishniac@wanginst.UUCP (Ephraim Vishniac) Newsgroups: net.micro.mac Subject: Re: Is My Thumb an Indicator? Message-ID: <1318@wanginst.UUCP> Date: Tue, 12-Nov-85 15:44:39 EST Article-I.D.: wanginst.1318 Posted: Tue Nov 12 15:44:39 1985 Date-Received: Wed, 13-Nov-85 04:01:34 EST References: <1283@wanginst.UUCP> Distribution: net Organization: Wang Institute, Tyngsboro, Ma. 01879 Lines: 28 > According to the Control Manager chapter of IM, the action proc for > a particular control will be called repeatedly as long as the mouse is > down in some part of the control. True enough, it will. It also says > that there are two flavors of action procs, depending on whether or not > the control is an "indicator". If it is, the action proc is a parameterless > procedure (no arguments, no return value). If not, the action proc > receives the control handle and part code as arguments. IM points out > that it's important to know what kind of control you're dealing with, > since "obviously" your action proc can only be of one type or the other. > > 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