World in Flames is the computer version of Australian Design Group classic board game. World In Flames is a highly detailed game covering the both Europe and Pacific Theaters of Operations during World War II. If you want grand strategy this game is for you.
The box is correct if the French have picked a combined action and are moving surface naval units, not submarines.
If the French have picked a combined, they have only one naval move. A naval move is one fleet moving to one sea box. Thus, in a combined, the French can't move units to two different locations, and the box is correct. This does not apply to submarines, where one naval move is all the submarines at one port moving to whatever destinations they like.
If the French have picked a naval, or if they are moving submarines, there is a bug. I rather suspect, though, that the French have picked a combined and are moving surface ships.