Using master (98958c81f5065a5de13699d46995d278ecb6709e) with Qt `5.12.3` (also tested with depends) with multiple wallets available. None are shown in the `Open Wallet ->` menu in the gui. The wallets can be loaded from the console, bitcoin-cli etc.
class OptionsModel;
class PlatformStyle;
class RPCConsole;
class SendCoinsRecipient;
class UnitDisplayStatusBarControl;
class WalletController;
class WalletFrame;
class WalletModel;
class HelpMessageDialog;
class ModalOverlay;
namespace interfaces {
class Handler;
class Node;
}
QT_BEGIN_NAMESPACE
class QAction;
class QComboBox;
class QMenu;
class QProgressBar;
class QProgressDialog;
QT_END_NAMESPACE
namespace GUIUtil {
class ClickableLabel;
class ClickableProgressBar;
}
/**
  Bitcoin GUI main class. This class represents the main window of the Bitcoin UI. It communicates with both the client and
  wallet models to give the user an up-to-date view of the current core state.
*/
class BitcoinGUI : public QMainWindow