306437 - change event fires twice for HTML select (mousedown & mouseup)

Status: VERIFIED FIXED

(Core :: Layout: Form Controls, defect)

Description

[Mike Caines]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8b4) Gecko/20050830 Firefox/1.0+
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8b4) Gecko/20050830 Firefox/1.0+

A change event is fired twice (as compared to Internet Explorer) when changing
the selection of an HTML select. One fires on mousedown and the other on
mouseup. If the same selection change is made with the keyboard, only one change
event is fired. The behaviour should be consistent.

Reproducible: Always

Steps to Reproduce:
1.Change the selection of the select element with the mouse
2.Note that the TWO alerts are displayed

Actual Results:  
Two alerts are displayed


Expected Results:  
One alert is displayed

Note the difference in change event firing between the mouse and keyboard, and
Internet Explorer and Mozilla (mouse).

Comment 1

[Mike Caines]

Attachment: Testcase

Comment 2

[zug_treno]

Reproducible with SeaMonkey/20050828 but WFM with Mozilla 1.8b1 and Deer Park a2.

Comment 3

[Ben Basson]

-> New, All/All. This is potentially a website breaking bug, so nominating for
1.8b5.

Comment 4

[Mike Caines]

This bug appeared in trunk builds of Firefox between 2005-07-14 and 2005-07-15.
It is probably the cause of bug 260850 also.

Could it be caused by one of these (esp. 291443)?
https://bugzilla.mozilla.org/buglist.cgi?query_format=advanced&short_desc_type=allwordssubstr&short_desc=select&long_desc_type=substring&long_desc=&bug_file_loc_type=allwordssubstr&bug_file_loc=&status_whiteboard_type=allwordssubstr&status_whiteboard=&keywords_type=allwords&keywords=&emailassigned_to1=1&emailtype1=exact&email1=&emailassigned_to2=1&emailreporter2=1&emailqa_contact2=1&emailtype2=exact&email2=&bugidtype=include&bug_id=&votes=&chfieldfrom=2005-07-14&chfieldto=2005-07-15&chfieldvalue=&cmdtype=doit&order=Reuse+same+sort+as+last+time&field0-0-0=noop&type0-0-0=noop&value0-0-0=

Comment 5

[Martijn Wargers (dead)]

It's better to use bonsai for determining which patch caused the bug:
http://bonsai.mozilla.org/cvsquery.cgi?treeid=default&module=all&branch=HEAD&branchtype=match&dir=&file=&filetype=match&who=&whotype=match&sortby=Date&hours=2&date=explicit&mindate=2005-07-14+05%3A00%3A00&maxdate=2005-07-15+08%3A00%3A00&cvsroot=%2Fcvsroot

Comment 6

[Scott MacGregor]

Looking at the test case, this seems like a pretty bad regression. Nothing
jumped out at me during the regression window.

Comment 7

[Scott MacGregor]

Bug 290354 made some event releated changes to an options element during the
regression window that could be related. 

Comment 8

[Martijn Wargers (dead)]

This is caused by the patch for bug 290354, backing out the listcontroleframe
part of that patch fixes the bug for me in my local debug build.

Comment 9

[Asa Dotzler [:asa]]

Aaron, this looks pretty nasty. Can you please help us get this fixed ASAP. I'd
like to not ship b4 with this problem.

Comment 10

[Aaron Leventhal]

Thanks Martijn, that was a great help. Backing out this small bit fixes it.

@@ -2708,6 +2718,9 @@ nsListControlFrame::MouseDown(nsIDOMEven
     // Handle Like List
     CaptureMouseEvents(GetPresContext(), PR_TRUE);
     mChangesSinceDragStart = HandleListSelection(aMouseEvent, selectedIndex);
+    if (mChangesSinceDragStart) {
+      UpdateSelection(); // dispatch event, update combobox, etc.
+    }
   } else {
     // NOTE: the combo box is responsible for dropping it down
     if (mComboboxFrame) {

Comment 11

[Aaron Leventhal]

Attachment: Don't know how the UpdateSelection() call snuck in. It's clearly wrong.

Comment 12

[[e-mail]]

Comment on attachment 194591 [details] [diff] [review]
Don't know how the UpdateSelection() call snuck in. It's clearly wrong.

I'm not a layout peer but the change looks good.

Comment 13

[Mike Schroepfer]

Verified on 9-5-07 Trunk build.   

Comment 14

[Tracy Walker [:tracy]]

verified on mozilla1.8 branch (Win, Lin and Mac) 2005-09-07