145541 - absolute positioned div are displayed incorrectly if top: auto and overflow: auto

Status: RESOLVED DUPLICATE of bug 145212

(Core :: Layout, defect, P1)

Description

[Roland Scheidegger]

From Bugzilla Helper:
User-Agent: Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.0rc2) Gecko/20020510
BuildID:    2002051006

If a div is positioned absolute and it has set top to "auto" (or not set at
all), and overflow to either "scroll" or "auto", it will not get displayed
correctly. If the text in the div is small enough so that no scrollbars appear,
nothing will be shown on screen, if the box has scrollbars the box itself is
drawn but not the content of the box. If there are links in the content, they
can be clicked however (if you hover over the non-visible link, mozilla will
show it in the status bar).

Reproducible: Always
Steps to Reproduce:
1. Open the testcase


Actual Results:  Nothing can be seen. If the window is small enough, a yellow
box is shown without content in the lower left edge. If you move the mouse over
that area (regardless if the box is shown or not) you will notice there's a link
in it.

Expected Results:  The div should be drawn correctly, i.e. the same as if
overflow is set to "hidden" or "visible".

Comment 1

[Roland Scheidegger]

Attachment: testcase

Comment 2

[Boris Zbarsky [:bzbarsky]]

Excellent testcase!  As a note, this works correctly for position:fixed, which
is a little surprising.  I bet this is related to bug 99978

Comment 3

[Roland Scheidegger]

I've just noticed that on solaris the testcase has a bit a different outcome.
Instead of showing nothing, the box is shown at the top left edge instead, if
the scroller doesn't appear. The link in the div is now both in the box at the
top and (invisible) at the bottom. If the window is small enough so the scroller
appears, the box is effectively doubled - one shows up at the top (with content,
without scrollbar), one at the bottom (only with invisible content, but with the
scrollbar). (Can't test this myself unfortunately on solaris with 1.0rc2, just
1.0rc1.).
As Boris Zbarsky mentioned, it works with position:fixed - at least almost: the
div is shown at the correct place, but it flickers at the top left edge if the
scroller is moved (looks the same as in <a href="show_bug.cgi?id="132337">bug
132337</a>)

Comment 4

[Kevin McCluskey (gone)]

More likely a view problem than layout.

Comment 5

[David Baron :dbaron: (⌚️UTC-5, no longer working on Mozilla)]

Why do you think that?

Comment 6

[Robert O'Callahan (:roc) (email my personal email if necessary)]

I'd say this is more likely layout, since the view system doesn't know anything
about "top: auto".

Comment 7

[David Baron :dbaron: (⌚️UTC-5, no longer working on Mozilla)]

Feel free to give this to "attinasi's list", or perhaps to bz, or to me, if you
really want to.

Comment 8

[Robert O'Callahan (:roc) (email my personal email if necessary)]

*** This bug has been marked as a duplicate of 145212 ***