GNOME Bugzilla – Bug 723151
GtkIconHelper (used by eg. CellRendererPixbuf) blocks while loading remote HTTP icons synchronously, freezing the whole application
Last modified: 2016-01-23 06:43:19 UTC
In the review of bug #723077 Bastien pointed out that stuffing GIcons pointing to remote images on a slow HTTP server in a GtkTreeView would make the application unusable as icons are resolved synchronously in the GtkIconHelper machinery used by GtkCellRendererPixbuf. For this reason, support for setting the proper source icon has been dropped from the above patch, but in general it would be nice to be able to use GLoadableIcon where needed and have GtkIconHelper work asynchronously.
IMO gtk shouldn't load GIcons from remote sources at all since it's basically the same as a web bug [https://en.wikipedia.org/wiki/Web_bug] but for gtk apps, and has no legitimate uses.