276087 - DOMAttrModified event isn't fired on binding

Status: RESOLVED INVALID

(Core :: DOM: Events, defect)

Description

[alexander :surkov (:asurkov)]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.8a5) Gecko/20041122
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.8a5) Gecko/20041122

I declare two bindings:

<binding id="binding1">
<content>
	<xul:textbox xbl:inherits="value=attr"/>
</content>
<handlers>
	<handler event="DOMAttrModified">
		alert("binding1"+event.attrName+"!"+event.attrNewValue);
	</handler>
</handlers>
</binding>

<binding id="binding2">
<content>
	<xul:binding1 xbl:inherits="attr"/>
</content>
<handlers>
	<handler event="DOMAttrModified">
		alert("binding2"+event.attrName+"!"+event.attrNewValue);
	</handler>
</handlers>
</binding>

I create:

<binding2 attr="2"/>

Event DOMAttrModified is fired for textbox but it isn't fired for binding1.

Reproducible: Always

Steps to Reproduce:

Comment 1

[alexander :surkov (:asurkov)]

I will say about strange behaviour of DOMAttrModified event. I don't know is it
different bugs or one the same.

I try:

<binding id="binding1">
<content>
	<xul:textbox/>
</content>
<implementation>
	<constructor>
		this.setAttribute('attr', this.getAttribute('attr'));
	</constructor>
</implementation>
<handlers>
	<handler event="DOMAttrModified">
		alert(event.attrName+"!"+event.newValue);
	</handler>
</handlers>
</binding>

<binding id="binding2">
<content>
	<xul:binding1 xbl:inherits="attr"/>
</content>
</binding>

When I create binding1 then DOMAttrModified is fired. When I create binding2
then DOMAttrModified is not fired.

Comment 2

[alexander :surkov (:asurkov)]

question: should DOMAttrModified event be fired for binding in the next case?

<binding1>
<content>
  <xul:textbox/>
</content>
<handlers>
  <handler event="DOMAttrModified">
     alert(event.newValue);
  </handler>
</handlers>
</binding>

<binding1 attr="4"/>

DOMAttrModified isn't fired when binding1 is created. Is it correct behaviour?

Comment 3

[Boris Zbarsky [:bzbarsky]]

Alexander, could you attach an actual testcase showing the problem?

Comment 4

[alexander :surkov (:asurkov)]

Attachment: bindings

Comment 5

[alexander :surkov (:asurkov)]

Attachment: styles

Comment 6

[alexander :surkov (:asurkov)]

Attachment: testcase for comment#0

DOMAttrModified is not fired for some elements in bindings (like xul:hbox) when
anonymous element has attribute or inherits it by xbl:inherits attribute. 
If I replace box with textbox then DOMAttrModified is changed.

Comment 7

[Boris Zbarsky [:bzbarsky]]

There should be no event firing for <xul:box attr="hello"/> (since the attribute
is set before there event handler is hooked up).

The event for <xul:box xbl:inhertis="attr"/> might fire if you spell "inherits"
correctly.

The events you see for the textboxes are probably for the "value" attribute, not
the "attr" attribute.

Comment 8

[Boris Zbarsky [:bzbarsky]]

OK, attrs set via inherits are set before the event listeners are hooked up. 
This makes sense, imo... Neil, thoughts?

Comment 9

[[e-mail]]

There is a mutation event fired when a textbox is bound. However, this isn't
caused by the textbox binding, it's actually caused by the textbox's context
menu which sets the textbox's context attribute to "_child" if it's unset. But
this is an attribute change on an element that's already in the document.

Comment 10

[alexander :surkov (:asurkov)]

Such behaviour is awkward. Why you don't want to hook up handlers before loading
content? Is it impossible? If I want to watch attributes changing then I want to
do it in one place. 

I suppose that answer of #comment2 question is 'no'. I belive it is awkard but
it is unachievable (because dom node is created before the binding).

Comment 11

[Boris Zbarsky [:bzbarsky]]

Hooking up handlers before setting up the content would be a pretty major
behavior change.  I don't think we can do that sort of thing at this point
without breaking compat with existing XBL content.