Window icons

From MDC

Starting with Firefox 1.5, Thunderbird 1.5, and XULRunner 1.8, you can specify an icon for a XUL window by putting files named mywindow.ico (for Windows) and mywindow.xpm (Linux), where mywindow is the id of the <window> you want to attach the icon to, in the chrome/icons/default subfolder of your bundle.

These icons will override the global icon files, which are located in app_dir/chrome/icons/default.

[edit] Older versions

To support older applications, such as Firefox 1.0, you need to copy the icons to app_dir/chrome/icons/default manually on the first start (example code).