When painting camouflage on a panzer, are the tools painted? What about when painting white over existing paint? The pictures in the instructions of the kit I have seem to indicate mostly so.
If camo was factory-applied, the tools would have been off. If field-applied, it would be up to the crew at times if they wanted to bother removing it all. Often slapping a little green or red-brown on them helped make the gear less obvious against the backdrop of the tank itself.
Whitewash would have been slapped over everything in most cases, as it wore off over time anyway and quite frankly, a bunch of dark objects rolling across a snowy plain would look kind of suspicious.
tl;dr There is no set rule. Find a pic that looks close to what you want and try to emulate what you see.