how to add legend type names in the plot browser display

I have started using the plot browser quite a bit for exploratory data analysis. When I add lines to plots, the 'DisplayName. can be used to add a name to the line in the plot browser side window (where one can toggle the visibility and/or delete the line). For some reason I cannot also do this for surface objects like 3d bar plots. Is there something I am missing? See the screen shot and notice how in this simple example the line is labeled in the plot browser window (as 'test2'), but the bar3 object is not -- even though the bar3 object is labeled in the legend (as 'test').