472083 - setting the background of a dialog window to transparent causes iframes to become invisible on the Windows XP platform

Status: UNCONFIRMED

(Core :: Layout, defect)

Description

[sdb]

User-Agent:       Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.0.5) Gecko/2008121623 Ubuntu/8.10 (intrepid) Firefox/3.0.5
Build Identifier: Firefox/3.0.5, Firefox/3.1b2, Firefox/3.1b3pre

If you have an xul dialog window that contains an iframe and you set the background of the dialog element to transparent it causes the entire window to disappear.  You can use other xul elements on top of the transparent background like an image element and they seem to work fine.  But for some reason the iframe element will disappear if it's displayed on top of a transparent background.  This bug ONLY occurs on Windows.  I've tested it in Ubuntu 8.10 64-bit using KDE 4.1 and everything works fine.  But for some reason Windows XP is incapable of displaying an iframe on top of a transparent dialog window.  I've also tested this issue in the latest beta versions of Firefox in Windows XP (v3.1b2 and v3.1b3pre) and the problem still exists.  I've also tried using a browser element instead of the iframe element and a window element instead of a dialog element and both options result in the same bug.

Reproducible: Always

Steps to Reproduce:

I've attached some test files in the post below.  You should be able to reproduce the bug using those files.  Simply add them to an extension and correct each of the urls in the source code and then open the test.xul file with the code below.

window.openDialog('chrome://extension/content/test.xul', '_blank', 'chrome=yes,alwaysRaised=yes,resizable=no', null);
Actual Results:  

On Ubuntu 8.10 everything works fine, but on Windows XP all you will see is the window's taskbar entry.  If you comment out the 'background: transparent' property in the style sheet and then open the window it will successfully display the iframe on top of a grayish background.

dialog, iframe {
	/*background:transparent !important;*/

Expected Results:  

All that should be visible in the xul dialog window is the png image.  All of the chrome should be hidden including the titlebar, borders, and background.

Comment 1

[sdb]

Attachment: test files to reproduce this bug

Comment 2

[sdb]

Attachment: test extension

You can use the attached extension to reproduce this bug.  After it's installed a "T" icon will appear on the statusbar.  Click the "T" icon to open the popup menu.  The "Open .... WITH" menuitem will open a dialog window that has been set to transparent.  The "Open .... WITHOUT" menuitem will open a dialog window that does not use the background:transparent property.  Both dialog windows contain an iframe element.  In Windows XP the dialog window with the transparent background will not show up at all.  In fact you can't even right click on the window's taskbar entry and close the window.  If you need to close the test windows simply click the "T" icon and select the "Close all test windows" menuitem.  Both dialog windows work fine in Ubuntu 8.10.  The transparency problem only occurs in Windows.

Comment 3

[Nickolay_Ponomarev]

Now that bug 298889 is fixed, is this still a problem?