unexpected messages

Richard Gaskin ambassador at fourthworld.com
Tue Apr 22 04:01:01 EDT 2003

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:


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.

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

 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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