Created attachment 109093
testcase - view with IE and Mozilla

I read this entire bug, and I disagree with people who says tooltips shouldn't
have newlines because the standard explicitly says that character entries
should be translated as I mentioned in comment 211 of bug 25537. There are
character entries for newlines, backspaces and tabs.

Now, I know you've heard the following before (just bear with me):

<!ENTITY % Text "CDATA">

CDATA is a sequence of characters from the document character set and may
include character entities. User agents should interpret attribute values as
follows: 

*Replace character entities with characters* [emphasis mine], 
Ignore line feeds, 
Replace each carriage return or tab with a single space.

Now, if you look at the test page I attached in IE 6, they do interpret &#10;
as a newline and &#9; as a tab, and although Microsoft is far from perfect when
it comes to standards, I would have to agree that it should be interpreted in
that way...

The reason is: Because its written that way in the spec. Also, since IE honors
this, it would satisfy people that Mozilla and IE had the same method for
adding a newline. When the standard seems ambigious, let's try to keep the
browsers of different groups/companies working the same (i.e. fill in the void
the standard left). We made a mistake in the past not rendering the background
of a table cell when it is empty because the standards said so when it seemed a
little ridiculous (People had to put in 1x1 gif images). Later, they modified
the standard and people still were hesitant about changing it (finally it was
changed). Until they make this less ambigious, let's just do what makes the
most sense from a web developer standpoint. I don't think having a multi-line
tooltip is out of the question. We can still crop each line and limit the
number of lines. In comment #56, there was a good example of when this might be
used. Anyway, if IE interprets &#10; as a newline, does it make any sense to
haggle over what the seemingly ambigious entry in the specs says when we are
only going to hear people complain about their pages "Not working in Mozilla"?

And anyway, it is following what the spec says: "Replace character entities
with characters". Unless you can find a part of the spec that says newline
characters shouldn't be displayed in tooltips, I don't see how it isn't clear
that we should escape &#10;


Therefore:
title="foo&#10;foo"
Display:
+---+
|foo|
|foo|
+---+

Therefore:
title="foo&#9;foo"
Display:
+----------+
|foo	foo|
+----------+


It says we should ignore line feeds (which I think by that they didn't mean
"\n" but meant hard lines feeds in the file). Note, again IE doesn't escape \n.


Therefore:
title="foo\nfoo"
Display as:
+--------+
|foo\nfoo|
+--------+

(Same with \t)
It says we should replace each carriage return or tab with a single space. I
think what they meant by that was when you have a CR-LF combination, the CR
should be turned into a space:

title="foo
foo"
Display:
+-------+
|foo foo|
+-------+

title="foo  (tab)  foo"
Display:
+-------+
|foo foo|
+-------+

....And notice how IE shows a nasty little blocky TAB char for:
alt="foo&#9;foo"
Let's not replicate that (Embrace and Improve) :-)