185758 - Move event flow out of elements

Status: RESOLVED FIXED

(Core :: DOM: Events, defect, P3)

Description

[John Keiser (jkeiser)]

Currently elements not only handle default actions for events, they also fire
the handlers for them and ensure that the event flow moves correctly.  This
logic is standard and should be moved to a standard place (ESM), and calls made
into the elements for things they need to do like default actions.  Things an
implementation will have to watch for:

- submit form controls set some bits while in the onclick handler for a
submission hack
- input type=file currently changes the target
- input type=radio, for compatibility reasons, sets .checked *before* the click
event is fired and sets it back if the default action was cancelled.
- eConsumeDoDefault, a very strange little status

More generally:
- things where elements override HandleDOMEvent and store state before and after
the event flow call to super::HandleDOMEvent() need to be handled still
- some elements need to know when default action was cancelled so they can
update their state

This will fix a number of problems that arise with the interaction between
elements that handle the same event by default: for example, with an <a href>
that contains an <input type=image>, the default handler is supposed to happen 

This will also make real event groups possible, and maybe even easy.

Comment 1

[John Keiser (jkeiser)]

It'd be good to have this in 1.4alpha; it looks like it will fix a number of
bugs and unblock further event work.

Comment 2

[John Keiser (jkeiser)]

As much as I hate to future this, I don't have time to fix this (which wouldn't
be awfully huge) and chase regressions (which would) until some of my other big
patches are out of the way.

Comment 3

[Alex Vincent [:WeirdAl]]

iirc, jkeiser is (per the terms of his current employment) prohibited from 
working on fixing bugs in Mozilla.  Should this go to the default owner?

Comment 4

[Olli Pettay [:smaug][[e-mail]]]

Event flow was moved to nsEventDispatcher in bug 234455.