Improve ui_get_mime_icon()

It may happen that even though we get GIcon, the actual icon dosen't exist (typically on Windows and OS X). Check if we can find the actual icon.

In addition, use "icon name" instead of "stock id" - the latter doesn't work on OS X / Windows for some reason.

src/ui_utils.c

@@ -2893,18 +2893,32 @@ GIcon *ui_get_mime_icon(const gchar *mime_type)
 	if (ctype)
 	{
 		icon = g_content_type_get_icon(ctype);
+		if (icon) 
+		{
+			GtkIconInfo *icon_info;
+
+			icon_info = gtk_icon_theme_lookup_by_gicon(gtk_icon_theme_get_default(), icon, 16, 0);
+			if (!icon_info)
+			{
+				g_object_unref(icon);
+				icon = NULL;
+			}
+			else
+				gtk_icon_info_free(icon_info);
+		}
+
 		g_free(ctype);
 	}
 
 	/* fallback if icon lookup failed, like it might happen on Windows (?) */
 	if (! icon)
 	{
-		const gchar *stock_id = GTK_STOCK_FILE;
+		const gchar *icon_name = "text-x-generic";
 
 		if (strstr(mime_type, "directory"))
-			stock_id = GTK_STOCK_DIRECTORY;
+			icon_name = "folder";
 
-		icon = g_themed_icon_new(stock_id);
+		icon = g_themed_icon_new(icon_name);
 	}
 	return icon;
 }