579259 - Black line painted in some windows

Status: RESOLVED FIXED

(Core :: Layout, defect)

Description

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

Load https://bugzilla.mozilla.org/enter_bug.cgi?product=Core. At the bottom left corner of the window I see a 1-pixel high row of black pixels just above the status bar.

Comment 1

[Aaron Train [:aaronmt]]

Same line visible on opening the preferences pane above the toolbar menu and disappears when you switch panes?

Comment 2

[bogas04]

Go to http://bugs.php.net/bug.php?id=40625.
Scroll to the bottom.
Click on Changes
Look at the artifacts on the page.

http://img694.imageshack.us/img694/2184/screenshotflx.png

Comment 3

[bogas04]

Attachment: Artifacts @ bugs.php

Comment 4

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

Hmm, I'm not seeing this on trunk today.

Comment 5

[Timothy Nikkel (:tnikkel)]

Bug 563878 could have affected this.

Comment 6

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

This is kind of a pain to reproduce. However, while working on another bug I saw a similar sort of line being drawn. I traced the problem down to a call to HIThemeDrawFrame, which was internally calling CGContextFillRects with the following rectangles:

  {origin = {x = 141, y = 284}, size = {width = 28, height = 1}},
  {origin = {x = -1.99741364,y = 1},size = {width = -0,height = -0}},
  {origin = {x = 1,y = 167},size = {width = 175,height = 1}}

Obviously the second rect is bogus, and the third rect is well outside the control. The behaviour is repeatable though.

Comment 7

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

Attachment: testcase

If you load this testcase, make the window really small vertically, and then resize it to make it taller, you can see that the visible width of the line is equal to the height of the listbox that is not visible.

This is clearly some kind of horrific bug in HIThemeDrawFrame.

Comment 8

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

Disabling retained layers in the BasicLayerManager fixes it.

Looking at the behaviour in that case, pre-retained-layers, the "bad line" is drawn at the bottom of the CGContext's destination surface, which with the status bar enabled is in the status bar and clipped out while we're drawing Web content. If I hide the status bar, I can see the bug with retained layers disabled (although I haven't verified it still occurs in a pre-retained-layers build).

Comment 9

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

OK, in my Firefox 3.6 build that I have lying around, if I disable the status bar I can see the bug!

Comment 10

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

I'm not sure what the best workaround is here.

We could clip to the widget overflow area around HIThemeDrawFrame. That would stop garbage randomly outside the themed element, but as the testcase shows, we can still show garbage within the element.

I thought fiddling with HIThemeOrientation might change things; it does, but only makes the bug appear in a different way (the length of the horizontal line is equal to the height of the element that is showing).

Passing kHIThemeFrameTextFieldSquare as the kind seems to have no problems. Can we do that? It's not visually identical to kHIThemeFrameListBox :-(.

We could draw the listbox frame by hand. That doesn't look hard.

Josh, Markus --- any suggestions?

Comment 11

[Markus Stange [:mstange]]

I don't see this, or I don't know what to look for. Can you attach a screenshot of the testcase?
Also, are you on 10.5 or 10.6?

Drawing the listbox frame by hand seems like the simplest solution to me. I might even have a patch for it lying around somewhere because at some point I was annoyed by the wrong colors - -moz-appearance:listbox is used by XUL trees, and native trees use slightly different border colors.

Comment 12

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

Attachment: FF3.6 screenshot

Note the horizontal black line at the left side of the bottom edge of the window. The listbox scrollbar overlaps it.

This is on 10.5.

I'd love to see a patch for Gecko drawing of the listbox frame. It looks pretty simple to me.

Comment 13

[Markus Stange [:mstange]]

OK, I definitely don't see this on 10.6.
Patch coming up.

Comment 14

[Markus Stange [:mstange]]

Attachment: patch

Comment 15

[Markus Stange [:mstange]]

http://hg.mozilla.org/mozilla-central/rev/9f225e37c7c7