Todo visible markings
It would be nice if we could somehow mark classes / attributes / operations, as todo items, as in "This operation needs to be implemented". It would be really helpfull if you could see it from the diagram, without clicking on it and reading the Documentation field. Anything from coloring it to dark red / any other color, to putting a dotted frame or making it's background a different shade/color/pattern, would tremendously help.
(not everyone can use the export tool (languages) - and it's kind of hard to keep track of an ongoing written project with the diagram, if more people work on it and/or you upgrade classes but don't have the time to actually write them.