icon selector accepts internal icons during value validation

web/htdocs/valuespec.py

@@ -3367,7 +3367,14 @@ def validate_value(self, value, varprefix):
         if not self._allow_empty and not value:
             raise MKUserError(varprefix, _("You need to select an icon."))
 
-        if value and value not in self.available_icons():
+        def is_internal_icon():
+            if defaults.omd_root:
+                base_path = defaults.omd_root+"/share/check_mk/web/htdocs/images"
+            else:
+                base_path = defaults.web_dir+"/htdocs/images"
+            return os.path.exists(base_path+'/icon_'+value+'.png')
+
+        if value and value not in self.available_icons() and not is_internal_icon():
             raise MKUserError(varprefix, _("The selected icon image does not exist."))