As stated in the topicname, it would be nice if the selected object while in LightmapDensityViewmode (LDVM) would just have the thick orange contour like in lit mode.
The purpose of being in LDVM is to check the lightmap density and alter them to your desired rez. If you have anything selected, the lightmap density pattern and especially the density color is not visible. You have to deselect the object to see the effect of altering the lightmap values, select again to alter again etc.