294897 - paint borders of parent elements after child's attributes have been painted

Status: RESOLVED INVALID

(Core :: Layout, defect)

Description

[Aaron Slunt]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8b2) Gecko/20050515 Firefox/1.0+
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8b2) Gecko/20050515 Firefox/1.0+

The borders of parent elements need to be painted after the child's attributes,
say for example, background color, are painted. The reason is that using
-moz-border-radius, the child's background can overlap and actually go outside
of the parent's border.

Notice this in the testcase: the top div shows the child background overlapping,
while the bottom div shows the child background overlapping and being painted
outside of the border. I realize that -moz-border-radius isn't exactly valid
css, but if this is the way that css3's border-radius will be implemented in the
future, then this should be taken care of.

Reproducible: Always

Comment 1

[Aaron Slunt]

Attachment: testcase showing painting problems

Comment 2

[Martijn Wargers (dead)]

Why do you think this is a bug?
Child elements can always go outside a parent element and then they get painted
on top of the parent element, obscuring the parent element. I would not expect
it that the child element gets clipped at those parts just because the parent
element has border-radius set.

If you want those painting problems solved, you can always use border-radius on
the child element.

Comment 3

[Aaron Slunt]

I think it's a bug, because...think about it, if a border-radius is set on a
parent, the designer more than likely wants everything to be contained in the
parent's border. I wouldn't want a child's background color to go outside of the
its container.

Comment 4

[Aaron Slunt]

(In reply to comment #3)
> I think it's a bug, because...think about it, if a border-radius is set on a
> parent, the designer more than likely wants everything to be contained in the
> parent's border. I wouldn't want a child's background color to go outside of the
> its container.

Lemme add, that the width of the child div in the testcase is 100% of its
parent, meaning it's designed to head the parent. I can understand what you're
saying if it was over 100%, but putting it to span the parent, imo, shouldn't
cause it to overlap any borders.

Comment 5

[Boris Zbarsky [:bzbarsky]]

The CSS spec defines the painting order very clearly and we're following it.