Custom properties as Alert Widget filters

Please add the ability to use group custom properties to the Alert widget filter.  At the moment we have to break our device group taxonomy if we want to exclude one particular group that is several levels down in the hierarchy.  If we had the ability to include/exclude device groups by custom property value then we could retain our device group taxonomy and include or exclude groups from the Alert widget based on a device group's custom property value.

You could take this a step further by allowing Applies To functions to be used with the Alert widget filter.  This could provide for very complex alert widget filters.