Scenario: The Silver Dragon is connected to a group of six green dragon panels. Player plays Move A Card (the green action) which changes the Silver Dragon to green – but the card they move is one of the green ones, which they move away, to break up the group. Does Green win in the middle of the execution of NotGreen’s Action?
A: Unless this is the very first Action played of the game, NotGreen can choose to play the Move a Card to the bottom of the discard pile, utilizing it’s power to move a card, but not changing the color of the Silver Dragon at all. This would be the wisest way to play that card in this case. This is always an option unless it’s the first Action card played in the game, in which there is no discard pile yet to put the card under. Keep in mind a player also has the option of playing the Action to the top of the pile to change the color, but not utilizing the power of the card.
If, for some reason, NotGreen still wanted to change the Silver Dragon to green, we would still rule that Green does not win, since all effects of Actions are considered to be simultaneous. So JUST as you add another green dragon (in the form of the Silver) you simultaneously take one away, and the total remains six, never having actually reached seven.
If, by chance, this IS the very first Action played of the game, however… the question is actually moot. If no Actions have yet been played, then the Silver Dragon is wild, and Green would have already won when the sixth green card was played to the group connected to the Silver Dragon.