Form element rendering regression

Hi!

Since several weeks/months KHTML exposes a somewhat ugly rendering
problem. It manifests itself as a block of elements (always form elements
I believe) being rendered at a wrong place of the screen unless one
performs an action like scrolling.

Steps to reproduce (credit go to Teve):

1.) Browse to http://marc.info/?l=kde-core-devel&r=2&b=200806&w=2

2.) Assure that the window is small enough to require scrolling

3.) Scroll down to the bottom of the page

4.) Press next

More often than not one now sees the Search field and buttons being shown
at the top of the page although they should be out of the visible area.

If the effect does not show try to navigate a bit with Prev and Next from
a scrolled down position.

Harri.

[Germain Garand-2]

Le jeudi 3 juillet 2008, Harri Porten a écrit :

> Hi!
>
> Since several weeks/months KHTML exposes a somewhat ugly rendering
> problem. It manifests itself as a block of elements (always form elements
> I believe) being rendered at a wrong place of the screen unless one
> performs an action like scrolling.
>
> Steps to reproduce (credit go to Teve):
>
> 1.) Browse to http://marc.info/?l=kde-core-devel&r=2&b=200806&w=2
>
> 2.) Assure that the window is small enough to require scrolling
>
> 3.) Scroll down to the bottom of the page
>
> 4.) Press next
>
> More often than not one now sees the Search field and buttons being shown
> at the top of the page although they should be out of the visible area.

Just to note I could reproduce that bug indeed.
I don't see it being related to widgets though, and rather than a block
rendered at the wrong place, I observe a block drawn at the correct place,
but over previous content that is not erased.

Could be backingstore/scrolling related. Or a bug in background painting of
replaced elements.

Greetings,
Germain

[Harri Porten]

On Wed, 16 Jul 2008, Germain Garand wrote:

> Just to note I could reproduce that bug indeed.
> I don't see it being related to widgets though, and rather than a block
> rendered at the wrong place, I observe a block drawn at the correct place,
> but over previous content that is not erased.
>
> Could be backingstore/scrolling related. Or a bug in background painting of
> replaced elements.

On a 2nd look I have to confirm your observation. It looked as if the
block was at the wrong place but what indeed happened was a scrolling of
the page with some of the content being stuck in its original position.

Harri.

On Wednesday 16 July 2008, Germain Garand wrote:

> Le jeudi 3 juillet 2008, Harri Porten a écrit :
> > Hi!
> >
> > Since several weeks/months KHTML exposes a somewhat ugly rendering
> > problem. It manifests itself as a block of elements (always form elements
> > I believe) being rendered at a wrong place of the screen unless one
> > performs an action like scrolling.
> >
> > Steps to reproduce (credit go to Teve):
> >
> > 1.) Browse to http://marc.info/?l=kde-core-devel&r=2&b=200806&w=2
> >
> > 2.) Assure that the window is small enough to require scrolling
> >
> > 3.) Scroll down to the bottom of the page
> >
> > 4.) Press next
> >
> > More often than not one now sees the Search field and buttons being shown
> > at the top of the page although they should be out of the visible area.
>
> Just to note I could reproduce that bug indeed.
> I don't see it being related to widgets though, and rather than a block
> rendered at the wrong place, I observe a block drawn at the correct place,
> but over previous content that is not erased.
>
> Could be backingstore/scrolling related. Or a bug in background painting of
> replaced elements.

The same bug (I think) happens when submitting a mailman form, which leads us
back to the same URL, but at the top of the page. The top of the page isn't redrawn,
so while the scrollbar is at y=0, one can still see the stuff that was at the bottom of the
form.
I can provide you with a list moderator password for a mailing-list if needed :)

--
David Faure, faure@..., sponsored by Trolltech to work on KDE,
Konqueror (http://www.konqueror.org), and KOffice (http://www.koffice.org).