The officer that said the whole gun needs to be visible is incorrect. Here is the law:
"18.2-308 A. If any person carries about his person, hidden from common observation, (i) any pistol, revolver, or other weapon designed or intended to propel a missile of any kind by action of an explosion of any combustible material...
...For the purpose of this section, a weapon shall be deemed to be hidden from common observation when it is observable but is of such deceptive appearance as to disguise the weapon's true nature."
So, as long as someone observes it and can tell it is a gun and not a can opener, it is considered open carrry. I open carry with a IWB much of the time without a second thought or problem.
A pen gun, for example, would always be considered concealed, even if laying on a table, because you can't tell it is a gun. There is also a belt buckle holster for the NAA 22LR micro revolver. Even though the gun would be in plain view on the front of that belt buckle, it would actuallly be considered concealed as no one would guess it was real.
Hope that helps.