187665 - Javascript event-handler defined with "document.onmouseover" may behave inconsistently

Status: RESOLVED EXPIRED

(Core :: DOM: Events, defect)

Description

[Gerrit Zimmermann]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.3a) Gecko/20021212
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.3a) Gecko/20021212

in JavaScript an event-handler definied for onMouseOver should be called each
time the mouse passes over a DOM-object. This is true, if 
1) all DOM-objects exist at loading (i.e. have been defined in the original
html-document).
or 2) user-created objects (with javascript-functions "newDiv =
document.createElement("div")" and
"document.getElementById(ParentObjectID).appendChild(newDiv)") are appended only
to objects existing at loading

If multiple childNodes are appended to one another some objects will no longer
spawn the onMouseOver-event.

Reproducible: Always

Steps to Reproduce:
A page demonstrating the problem can be found at the given URL.

1. Load page
2. Click and Drag Mouse anywhere on the page. A new "div"-object is created.
3. Move Mouse into and out of the new object. Watch the two input-fields. They
should give the id of the object, the mouse is currently positioned over and a
count of how often the event-handler has been called.
4. Repeat steps 2. and 3. If the second (and forth and so on) newly created
object is created inside another "div"-object, it is appended to it as a
childNode; otherwise the object's parent becomes the "body"-element; as long as
all created objects are siblings, behaviour is as expected. Otherwise some
objects won't spawn the onMouseOver-event any longer (always the same objects
for a given configuration of the tree).
Actual Results:  
See text above.

Expected Results:  
See text above.

Seems to be system-independent (occured on W2K and W98SE), could be reproduced
with Mozilla 1.0, 1.1 and 1.3a (1.2 not tested).

Comment 1

[Ruslan Ismailov]

Sorry, but you script contains an error. In this line:

newDiv.style.top = Event.pageY -
parseInt(document.getElementById(LastObjectID).style.top);

See, Event.pageY get mouse coordinated from body box, and style top -- is
distance between two included boxes, so third box top evaluated incorrecly. Look
here:
--------------------------------------------------
Body box    ^
            |  style.top for 1th div
            V
------------------------------------------------------------
|                  ^
| 1th div          |   this is style.top for 2nd div
|                  V
|   --------------------------------------
|   |                                    |
|   |        x <--- Mouse pressed here   |
|   |                                    |
|   --------------------------------------
------------------------------------------------------------

so right value should be PageY - style.Top(2nd div)  - style.Top(1th div)

Comment 2

[Gerrit Zimmermann]

Ok, Ruslan, you were right. I corrected the script's behaviour, but the error
stays the same.

Comment 3

[Ruslan Ismailov]

Sorry, there are another bug, linked with border-width, that you don't count in 
evaluateParams(). You better try position:fixed div's (absolute positioned
elements are awesome to scripting). I made a testcase for it.

Comment 4

[Ruslan Ismailov]

Attachment: Same testcase with position:fixed div's

Sorry, I could not do the same job with position:absolute -- it brain me out.

Comment 5

[Boris Zbarsky [:bzbarsky]]

I bet the real issue is the positioning, anything else...

Comment 6

[Gerrit Zimmermann]

Call me dumb, but this really seems to be some obscure error in my script. 

With a *much* simplified Version (http://data-development.de/rd/js/working.html)
of the test-script the supposed error disappeared.

Comment 7

[Gerrit Zimmermann]

So now I've really made a fool of myself. I checked (and refined) my original
script quite thoroughly now and am sure the behaviour I described is no error of
mine.
The error occurs only if the objects created are resized by capturing
onMouseMove; if created with fixed width or resized only once (onMouseUp)
everything works as expected. So this might not be a real showstopper, since I
found a way to work around it, but it is an error nevertheless.

I've created two scripts to show the error. One is a working implentation, the
other has the error. The scripts differ in some object-juggling, only.

Working: http://www.data-devlopment.de/rd/js/testcase1.html
Error: http://www.data-devlopment.de/rd/js/testcase2.html

Comment 8

[Phil Schwartau]

At any rate, this is not JS Engine. Reassigning as a guess
to DOM Events for further analysis -

Comment 9

[Vladimir Ermakov]

The site is not up, can you please attach the testcases to the bug?

Comment 10

[Daniel Wang]

Comment on attachment 110657 [details]
Same testcase with position:fixed div's

reporter (Gerrit Zimmermann),
http://www.data-devlopment.de/rd/js/testcase1.html and testcas2.html are
not working. can you post the testcases as attachment?

(related? bug 14692)

Comment 11

[Gervase Markham [:gerv]]

This is an automated message, with ID "auto-resolve01".

This bug has had no comments for a long time. Statistically, we have found that
bug reports that have not been confirmed by a second user after three months are
highly unlikely to be the source of a fix to the code.

While your input is very important to us, our resources are limited and so we
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Comment 12

[Gervase Markham [:gerv]]

This bug has been automatically resolved after a period of inactivity (see above
comment). If anyone thinks this is incorrect, they should feel free to reopen it.