Bug in
Firefox Related to Autocomplete Dropdown Lists
I know that this bug has been reported several times but it has not been eliminated.
I've come across an error that almost drove me crazy as I tried to
figure out why and when it was occurring. It was an intermittent error
(not occurring
every time I did something with FF) that I was
seeing as I worked on some PHP code and web pages. I have a second
monitor on this computer and after I saw these error occurring at what
seemed random times, I opened the FF Error Console on one monitor and
then worked on the task at hand on the other so that I could see the
errors right when they occurred.
I first stopped using the system and let it sit there for about 30
minutes to make sure that FF wasn't toss out these errors all by
itself. The error did not occur.
Then I went to the page I was working, testing a form and some PHP
code, and began doing the things I had been doing when I first realized
that this error was occurring. The only symptom of this
problem is the error message which is put in the
Error Console.
I finally found what I was doing which caused the error and I'm now to
reproduce the error at will. If you want to skip to the instructions to
reproduce the error, click here
- However, I recommend you read the rest of this page at least once
before you try to reproduce the error.
On the page I was testing, I have some Input HTML tags to create
textboxes and the problem
concerns textboxes and the FF Autocomplete feature. If I
double click,
on one
of my textboxes, into which I had previously entered values as I tested
the page,, the dropdown list appears showing the values I have
previously entered into the text box.
If I move my cursor down to one
of the values, causing FF to highlight the entry. I then move
my
cursor , without click
on the highlighted entry, to some other spot in the window
- that is, somewhere outside of the dropdown list -
and click with any mouse button and the
error message appears in the
Error Console. It does not matter which mouse button you click, the
error occurs. It even occurs if you roll the scroll wheel on the mouse.
Let me repeat that - it happens regardless of which
mouse button I click. I don't have a mouse with more than three buttons
but I wouldn't be surprised if this error is reproducible using 4th or
5th or whatever buttons on a mouse with more than three buttons.
1) pull up the list of previous values entered into text box. (do so by
double clicking the textbox, type the first character of a previously
entered value)
2) move the cursor down into the list so that an entry is highlighted,
it doesn't matter which one.
3) move the cursor off the dropdown list to some other spot on the page, leaving the entry highlighted in the dropdown list..
4) Click any mouse button or roll the scroll wheel on the mouse
- the error message will be written to the Error Console.
I've tried moving the cursor to blank spots, links, text, buttons - it
seems to make no difference what you click, the error occurs. Even if
you move the cursor to a link and click it, the error occurs. The link
you clicked will be followed but still the error occurs.
I am still using FF 3.6.24 on this system but I tested it on one of my
wife's systems which is running FF 14.0.1 and the error occurs on both
systems every time I want to reproduce it - it is a consistent error
using the steps I document below:
I have the Web Developer, version 1.9, add-on for FF install in FF
3.6.24 and I have set the options to pull up the Error Console if
errors occur: Here at the options available:
Warnings & Errors
Open Error Console when
the current page generates a CSS error
Open Error Console when
the current page generates a JavaScript warning
Open Error Console when
the current page generates a JavaScript error
I have all of those options "checked." When this error occurs, the
Error Console is NOT opened, or pulled to the top of the windows if
already open.
My question is fairly simple -
What the hell is going on here? I searched the FF bugs and found this
has been reported several times but it has not been fixed.
With Firefox 3.6.24 the error message in the
Error Console is:
Error:
uncaught exception: [Exception... "Cannot modify properties of a
WrappedNative" nsresult: "0x80570034
(NS_ERROR_XPC_CANT_MODIFY_PROP_ON_WN)" location: "JS frame ::
chrome://global/content/bindings/autocomplete.xml :: onxblpopuphiding
:: line 825" data: no]
I searched for the file, autocomplete.xml, on my system and could not
find it.
With Firefox 14.0.1, the message is:
Error:
NS_ERROR_XPC_CANT_MODIFY_PROP_ON_WN: Cannot modify properties of a
WrappedNative
Source
File: chrome://global/content/bindings/autocomplete.xml
Line:
916
I doubt that the link above, in the message which FF 14.0.1 creates,
will take you anywhere but it does when clicked in the Error Console
(in FF 14.0.1) It opens the file and positions to the line that was
being executed when the error occurred and the line is highlighted.
Here's
a link to the
file on my web site, here. I copied it to my server to allow
people to see the version on my wife's system with FF 14.0.1. That link
will open in a new tab. I've changed the extension of the
file from xml to txt to prevent any confusion on the part of FF when
trying to display it for you.
To find the line in the file that FF says
is where the error occurred, go to the file and search for: This is the
line where it failed
I have IE 8 on my system and I tried to produce the error with IE and
was unable to do so. I don't know about any other browsers, or other
releases of FF, but it does occur
on FF 3.6.24 and 14.0.1 and IE
When I first figured out how to reproduce this error, I thought that it
might be linked to the textbox losing "focus." I tried pressing the tab
key instead of clicking a mouse button, when the dropdown list is
visible and an entry is highlighted, but that does not produce the
error. Nor does it occur if I press the left of right arrow keys - that
simply selects the highlighted item and puts it in the textbox. It is
still possible that this has something to do with the textbox losing
focus. I haven't taken any time to look into the code.
Here, again and in more detail, is
how I can produce the error, every time I try, on my system (FF 3.6.24)
and my wife's system (FF 14.0.1):
1) - Type something into
the textbox below and press enter (with FF 3.6.24 pressing Enter may
not be needed) - the form's action URL is set a named anchor on this
page, it is just to the left of the word "Here's how I can produce the", above.
Pressing Enter "submits" the form without really going anywhere.
I have found that pressing enter is necessary on FF 14.0.1 to recreate
the error. FF 3.6.24 does not require that you press Enter after typing
something into the textbox (but if you have problems reproducing the
error, press Enter after you type something into the box). If you can't
get the dropdown list on FF 3.6.24 without pressing Enter, go ahead and
press Enter and the error should occur.
NOTE - with FF 14.0.1 there may be warning messages in the Error
Console which have to do with the form submission. Since I cobbled this
form together, just ignore the additional errors.
2) - Display the autocomplete dropdown box - one way is double click on
the box and a list showing the values
you've entered will be displayed (if this is the first time you messed
with this page, the list will only contain whatever you type in step 1
but it will make not any different in attempting to reproduce the
error) You could also clear the box and press the first letter of a
value you have typed into the box before and the dropdown list will
appear.
Note about IE 8 - you must first clear whatever is in the text box
before double clicking on it to pull up the dropdown list of values.
Move the cursor down into the list and highlight an item.
Then move the cursor off the list, to any blank spot on the window, and
click the left, center, or right mouse button - you can also roll the
scroll wheel and the error will occur.
3) - Open the error
console, you should see the error. Make sure that All or Errors is
selected at the top of Error Console so that Error messages will be
displayed.
Does anyone have any thoughts on
this error?
If so, go to my home
page
and Email Me. There is a link in the nav table on the left of my home
page.