gthumb doesn't display images correctly if the corresponding filename doesn't have an extension (the format doesn't seem to matter: I've tried on both a JPEG image and a PNG image). To reproduce the bug: 1. Copy a not-too-small image, where the filename has the extension associated with the format, e.g. "/tmp/file.jpg". For instance, /usr/share/doc/w3-recs/html/www.w3.org/TR/2007/REC-ws-policy-attach-20070904/ws-policyattachment-4-wsdl20.jpg from the w3-recs package can be used. 2. See what you obtain with gthumb on this file, e.g. "gthumb /tmp/file.jpg" (everything should be OK). 3. Remove the extension, e.g. "mv /tmp/file.jpg /tmp/file". 4. Run gthum on this new filename, e.g. "gthumb /tmp/file". Normally one should see no differences, but instead, one gets a very small image (small, but correct, so that the format has been detected correctly). Moreover the toolbar is incomplete: there is nothing between "Next" and "Tools", i.e. the zoom buttons are missing. Note: whether "Determine image type from content (slower)" is ticked or not in the Browser gthumb preferences doesn't matter.
Control: found -1 3:3.2.6-1+b1 With gthumb 3:3.2.6-1+b1, the small image flickers with endless assertion failures: [...] (gthumb:4461): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed (gthumb:4461): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed (gthumb:4461): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed (gthumb:4461): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed (gthumb:4461): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed (gthumb:4461): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed (gthumb:4461): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed (gthumb:4461): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed (gthumb:4461): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed (gthumb:4461): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed (gthumb:4461): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed (gthumb:4461): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed [...]