- Fix the "Cancel" button in the concede dialog box leading to an immediate game quit when conceding the match via the "X" button in the title bar.

forge-gui/src/main/java/forge/match/AbstractGuiGame.java

@@ -207,6 +207,8 @@ public abstract class AbstractGuiGame implements IGuiGame, IMayViewCards {
                     // Concede each player on this Gui (except mind-controlled players)
                     c.concede();
                 }
+            } else {
+                return false;
             }
             if (gameView.isGameOver()) {
                 // Don't immediately close, wait for win/lose screen