When is message passing required?

Mike Kerner MikeKerner at roadrunner.com
Mon May 23 10:35:33 EDT 2016

You only need to pass a message if you don't want another handler for that
message to possibly get in the way.  If you don't have a keyDown handler in
any of your scripts in the message path, the engine will get and handle it.

On Mon, May 23, 2016 at 9:13 AM, Paul Dupuis <paul at researchware.com> wrote:

> In LiveCode some messages must be passed to the engine for the engine's
> normal processing of the message. And with current versions of LC you
> have the very handy 'pass <message> to top' to send it directly to the
> engine.
> For example, rawkeyDown must be passed for LiveCode to handle key
> presses other than what you are trapping (unless you want all keypresses
> trapped). Some message line preOpenStack you don't need to pass. The
> stack still opens without passing a preOpenStack to the the engine.
> Does anyone have a compiled list of which messages need to be passed or
> *should* be passed vs those that you do not have to concern yourself with?
> In some dictionary entries, like for rawKeyDown, it talks about the need
> to pass the message (unless you want to trap all key presses). In other
> dictionary entries it is not clear whether the message needs to be
> passed or not. I am not sure that if it doesn't state one way or another
> assuming one way or another is wise.
> I know there have been some excellent flow charts of LiveCode's message
> passing hierarchy (Richard Gaskin's comes to mind) but I don't recall
> seeing any summation of which messages should be passed vs which do not
> need to be?
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