Merge bitcoin#15957: Show "No wallets available" in open menu instead…

… of nothing

c3ef63a Show loaded wallets as disabled in open menu instead of nothing (MeshCollider)

Pull request description:

  Fixes the confusing behavior reported in bitcoin#15952

  ![image](https://user-images.githubusercontent.com/3211283/57224284-0e8e7f80-705d-11e9-9554-2450cc3dbb8e.png)

ACKs for commit c3ef63:
  jonasschnelli:
    Tested ACK c3ef63a
  kristapsk:
    tACK c3ef63a

Tree-SHA512: fc2b94936ca32b89e8146c65e3629785883d78660afc8838818df652a4df9185ddca6b36ebf140a7159ab42b0fa5aa72867558d4572a009be06f0831fa813d1f

src/qt/bitcoingui.cpp

@@ -370,9 +370,18 @@ void BitcoinGUI::createActions()
         connect(openAction, &QAction::triggered, this, &BitcoinGUI::openClicked);
         connect(m_open_wallet_action->menu(), &QMenu::aboutToShow, [this] {
             m_open_wallet_action->menu()->clear();
-            for (std::string path : m_wallet_controller->getWalletsAvailableToOpen()) {
+            std::vector<std::string> available_wallets = m_wallet_controller->getWalletsAvailableToOpen();
+            std::vector<std::string> wallets = m_node.listWalletDir();
+            for (const auto& path : wallets) {
                 QString name = path.empty() ? QString("["+tr("default wallet")+"]") : QString::fromStdString(path);
                 QAction* action = m_open_wallet_action->menu()->addAction(name);
+
+                if (std::find(available_wallets.begin(), available_wallets.end(), path) == available_wallets.end()) {
+                    // This wallet is already loaded
+                    action->setEnabled(false);
+                    continue;
+                }
+
                 connect(action, &QAction::triggered, [this, name, path] {
                     OpenWalletActivity* activity = m_wallet_controller->openWallet(path);
 
@@ -400,6 +409,10 @@ void BitcoinGUI::createActions()
                     assert(invoked);
                 });
             }
+            if (wallets.empty()) {
+                QAction* action = m_open_wallet_action->menu()->addAction(tr("No wallets available"));
+                action->setEnabled(false);
+            }
         });
         connect(m_close_wallet_action, &QAction::triggered, [this] {
             m_wallet_controller->closeWallet(walletFrame->currentWalletModel(), this);