Merge #16118: gui: Enable open wallet menu on setWalletController

75485ef gui: Enable open wallet menu on setWalletController (João Barbosa)

Pull request description:

  `BitcoinApplication::initializeResult` and `BitcoinGUI::setWalletController` are only called after the startup rescan is completed. While the rescan is in progress the window menus are already available.

  This PR makes the Open Wallet menu disabled until `BitcoinGUI::setWalletController` is called.

  ![Screenshot 2019-05-29 at 14 17 48](https://user-images.githubusercontent.com/3534524/58560510-35377480-821d-11e9-8f96-d0573c9e47b0.png)

  Fixes #16087

ACKs for commit 75485e:
  jonasschnelli:
    utACK 75485ef
  ryanofsky:
    utACK 75485ef. It's a simple, sensible fix.

Tree-SHA512: 9395ceed54bbceb6cbf1cd443f783d07a6ebb8fc5515b63c6e1b8b19b216b08d1cba7eaf872814d7c426ab7192f3b416ba0d57fc84f3bcbfebf01ce153794201

Author: fanquake

src/qt/bitcoingui.cpp

@@ -335,7 +335,7 @@ void BitcoinGUI::createActions()
     openAction->setStatusTip(tr("Open a bitcoin: URI or payment request"));
 
     m_open_wallet_action = new QAction(tr("Open Wallet"), this);
-    m_open_wallet_action->setMenu(new QMenu(this));
+    m_open_wallet_action->setEnabled(false);
     m_open_wallet_action->setStatusTip(tr("Open a wallet"));
 
     m_close_wallet_action = new QAction(tr("Close Wallet..."), this);
@@ -633,6 +633,9 @@ void BitcoinGUI::setWalletController(WalletController* wallet_controller)
 
     m_wallet_controller = wallet_controller;
 
+    m_open_wallet_action->setEnabled(true);
+    m_open_wallet_action->setMenu(new QMenu(this));
+
     connect(wallet_controller, &WalletController::walletAdded, this, &BitcoinGUI::addWallet);
     connect(wallet_controller, &WalletController::walletRemoved, this, &BitcoinGUI::removeWallet);