The default (Firefox-supplied) icons in the directory viewer need hidpi version, so they don't look blurry (upscaled) on Retina displays. This is the viewer used for file:/// and ftp://ftp.mozilla.org/ * Folder icons * tab favicon (both file:// and ftp:// versions) * "Up to higher level directory" icon Note that we correctly use hidpi icons for files which have a known handler (via moz-icon, I assume).
These icons are in toolkit/themes/osx/global/dirListing/ Except the file:/// flavor isn't. Hmmm. *pokes* Oh, FFS, it's coming from down in netwerk/streamconv/converters/nsIndexedToHTML.cpp#433 as a data: URI. Bug 388553. Is that still a problem? I thought we fixed that sometime in the last year or two. If not, we should consider doing a front-end hackaround. [Aside: C++ code emitting big blobs of hard-coded HTML+JS+images makes me sad.]