.messageImage of the notification bar for the 'BigFile/FileLink' message as 'src=null' which means that it won't display any message icon, even if 'list-style-image' is applied from /skin/. What is expected that there is a nice warning or info icon for this notification bar. How to fix: Remove the 'src=null' from the .messageImage element. Or more specifically: In bigFileObserver.js: 117 nb.appendNotification(this.formatString("bigFileDescription", 118 [this.bigFiles.length], 119 this.bigFiles.length), 120 "bigAttachment", "null", nb.PRIORITY_WARNING_MEDIUM, 121 buttons); Replace the "null" with null.

Hm. So it looks like we do this in a few other places... Notably here: http://mxr.mozilla.org/comm-central/source/mail/components/compose/content/MsgComposeCommands.js#1993 It looks like it's done intentionally in order to bypass the default images and allow overriding with a new icon in CSS. That's what the comment suggests, anyhow.

Blake: You worked on the attachment reminder bar - any comment on this? -Mike

Re comment 1: passing "null" means that the icon CANNOT be set from CSS. If null (without the " quotes) is passed the icon will be left empty and canbe set from CSS.

So the icon is not used in base TB, but you want the support to be there in case some theme/extension wants an icon there? Or do you propose to add some icons also in base TB?

It is just about replacing "null" with null, so just to remove the quotes.