unexpected messages

Bob Rasmussen brasmussen at earthlink.net
Tue Apr 22 23:32:00 EDT 2003

Richard Gaskin <ambassador at fourthworld.com> wrote:

> Bob Rasmussen wrote:
> > I just spent a couple hours tracking down a problem that turned out to result
> > from an unexpected "mouseMove" message on a "hide object" command (while the
> > mouse button was down, but before the mouse had actually moved).  Not only did a
> > mouseMove message get generated, but it appears to have preempted the currently
> > running handler. That's what caused my problem, since I wasn't expecting the
> > first mouseMove message until after the mouseDown message handler finished. I
> > haven't found any documentation of this.
> >
> > More generally, it would be useful to have a summary somewhere of what triggers
> > system messages, and when. Most are documented somewhere in the Transcript
> > Dictionary (though not always in detail), and most are intuituve, but this one
> > caught me by complete surprise. The debugger wasn't helpful due to the need to
> > trap just after a mouse click. Once I figured out that a mouseMove message was
> > coming from somewhere (thanks to UmbrellaMan), it was still hard to narrow down
> > the source, because I kept looking in all the wrong places. Who would have
> > expected "hide"?
> >
> > Does anyone have such a list?
> You can watch messages logged to a console as they are generated in the
> UmbrellaMan utility at:
> <http://www.fourthworld.com/rev/>

Yes, as I described in my original note.  Thanks.

> However, both mouseMove and idle are omitted from UmbrellaMan's list of
> messages that can be logged, as they are sent so often that they'd flood the
> log with uninteresting entries.

Nevertheless, I found UmbrellaMan useful because I could trace messages issued from the
mouseMove handler.

> The mouseMove messaage is sent whenever the mouse is moved, regardless is
> the state of the mouse button.

But, as I noted, the mouse had *not* moved.  The mouseMove message was triggered by a "hide"
command in a mouseDown handler, *not* by any mouse movement.  Why?  And what other surprises are
in store?

> --
>  Richard Gaskin
>  Fourth World Media Corporation
>  Developer of WebMerge 2.2: Publish any database on any site
>  ___________________________________________________________
>  Ambassador at FourthWorld.com       http://www.FourthWorld.com
>  Tel: 323-225-3717                       AIM: FourthWorldInc

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