Try disabling the Take a card menu item in the BlackJackPlayerView visual part for the same conditions that prevent a drop. One way to do this is to create a boolean attribute in BlackJackPlayerView and enhance canTakeCard to set it. For example:
canTakeCard "Answer false if the player has a 5-card trolley, a winning hand (21), or is busted (over 21)." | sum items result | sum := 0. items := (self subpartNamed: 'Container Details1') items. items do: [:card | sum := sum + (card rank)]. result := (items size > 4 or: [sum > 20]) not. self canAcceptCard: result. ^result