204200 - cannot scroll to the bottom of the page

Status: RESOLVED FIXED

(Core :: Layout: Positioned, defect, P3)

Description

[Jakub Narebski]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.3; MultiZilla v1.4.0.2) Gecko/20030314
Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.3; MultiZilla v1.4.0.2) Gecko/20030314

In the page http://www.devastation.pl and subsequent pages, when the page is
tall enough that it requires scrolling (you can make tha page tall enough by
enlarging the font size) I cannot scroll to the bottom of the page. When I
scroll to the bottom there is some text which is below the bottom of the window
and is not visible. This can be seen by looking at the source of the page or by
lessening the font size.

I dont know if it is the Mozilla bug or the erron in the page, but even if the
page is not coded right the Mozilla should "work around" this error.

Reproducible: Always

Steps to Reproduce:
1.Open the page
2.Enlarge font until scrollbar appears, if needed
3.Scroll to the bottom of the page

Actual Results:  
The bottom of the page is not visible and flows from the Mozilla window.

Expected Results:  
The bottom of page should be visible.

Comment 1

[Bill Mason]

This is because of the invalid and probably only tested in IE CSS:

#maindiv {
        position: absolute;
        left: 130;
        top: 107;
        width: 583;
        height: 100;
        visibility: visible;
}

Height 100 what?  And setting height to 100 anything means if the content is
larger, you don't see it.

->TE

Comment 2

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

No, this is a real bug.

Comment 3

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Please note that just because a page contains invalid CSS that we correct in
quirks mode doesn't mean the bug is invalid.

Comment 4

[Jakub Narebski]

Even if the CSS of the mentioned page is wrong, Mozilla must have made some
assumptions and tried to correct it to display this page. Something like using
pixels when units are not specified.

For absolute positioning 'overflow: visible' is default (according to CSS2.1
specification). It looks like Mozilla in calculating the width of the page takes
into account only calculated or given in CSS height of the box, and does not
take into consideration the situation where text height is larger than height of
the box, and there should be provided place to render it outside the block box.
I.e. Mozilla should [almost] always use the max of the height of the text and
the height of the box in calculating the height of the page (used in scrolling).

I tried to make simplified testcase with absolutely positioned div box with
height smaller than height of its contents, and scrolling works O.K.

Comment 5

[Marek Stępień [:marcoos, inactive]]

I don't think that this is really a Mozilla bug. Exactly the same problem occurs
in Konqueror 3.1 and Opera 7.11/Linux.

This should be simply Tech Evangelism -> Central Europe. 

Comment 6

[Jakub Narebski]

Has anyone tried to reproduce this bug with simple testcase? I tried and failed,
as described in comment #4.

Comment 7

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

If the page is using 'overflow: hidden' then it *could* be correct behavior.  If
it's not using 'overflow: hidden', then Mozilla's behavior is incorrect.

Comment 8

[Marek Stępień [:marcoos, inactive]]

Attachment: Simplified testcase for this not_bug :)

Simplified testcase of ugly HTML used in devastation.pl

Comment 9

[Marek Stępień [:marcoos, inactive]]

What devastation.pl does, is that they have an absolutely positioned div
("maindiv") in an relatively positioned one ("tlo"), which is put into a table.

This is really weird, but I think (I am nearly sure) that what Mozilla,
Konqueror and Opera do is CORRECT, and what IE does - is WRONG.

This really should be TE->Europe: Central.

Comment 10

[Boris Zbarsky [:bzbarsky]]

Um... that would a dup of the "tables do not propagate overflow area" bug, no?

Comment 11

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Yes, which is a known, real, bug.  (Although bug 173277 is the only bug report
on it that I can find right now.)

Comment 12

[Jakub Narebski]

Attachment: Simplified testcase #2 which VALIDATES

This is the simplified testcase of the layout used in http://devastation.pl,
which is rendered incorrectly in Mozilla, i.e. absolutely positioned div with
given size inside relative positioned div (which may be not important), inside
table with given size. All elements have color borders to let one see the block
structure.

This file uses valid CSS (inline) and is valid HTML.

Comment 13

[Mats Palmgren (inactive)]

Attachment: Testcase #3

Comment 14

[Mats Palmgren (inactive)]

This was mostly fixed by bug 173277.  There is still a scrollbar problem
though as can be seen in "Testcase #3"

Comment 15

[Oleg Sidletskiy]

duplicate/related: bug 194822?

Comment 16

[Bernd]

this looks very similiar to bug 231275

Comment 17

[Bernd]

fixed by the patch in231275