simplified toggle boolean

[ci skip]

src/main/java/org/cryptomator/ui/mainwindow/MainWindowTitleController.java

@@ -63,11 +63,7 @@ public class MainWindowTitleController implements FxController {
 		});
 		titleBar.setOnMouseClicked(event -> {
 			if (event.getButton().equals(MouseButton.PRIMARY) && event.getClickCount() == 2) {
-				if (window.isFullScreen()) {
-					window.setFullScreen(false);
-				} else {
-					window.setFullScreen(true);
-				}
+				window.setFullScreen(!window.isFullScreen());
 			}
 		});
 		titleBar.setOnMouseDragged(event -> {