Don't show multiple unlock UI dialogs. Closes #2040.

src/mainwindow.cpp

@@ -101,7 +101,7 @@ using namespace libtorrent;
  *****************************************************/
 
 // Constructor
-MainWindow::MainWindow(QWidget *parent, const QStringList& torrentCmdLine) : QMainWindow(parent), m_posInitialized(false), force_exit(false)
+MainWindow::MainWindow(QWidget *parent, const QStringList& torrentCmdLine) : QMainWindow(parent), m_posInitialized(false), force_exit(false), unlockDlgShowing(false)
 #ifdef Q_OS_WIN
 , has_python(false)
 #endif
@@ -686,8 +686,14 @@ void MainWindow::setTabText(int index, QString text) const {
 }
 
 bool MainWindow::unlockUI() {
+  if (unlockDlgShowing)
+    return false;
+  else
+    unlockDlgShowing = true;
+
   bool ok = false;
   QString clear_password = AutoExpandableDialog::getText(this, tr("UI lock password"), tr("Please type the UI lock password:"), QLineEdit::Password, "", &ok);
+  unlockDlgShowing = false;
   if (!ok) return false;
   Preferences* const pref = Preferences::instance();
   QString real_pass_md5 = pref->getUILockPasswordMD5();

src/mainwindow.h

@@ -183,6 +183,7 @@ private:
   bool displaySpeedInTitle;
   bool force_exit;
   bool ui_locked;
+  bool unlockDlgShowing;
   LineEdit *search_filter;
   // Keyboard shortcuts
   QShortcut *switchSearchShortcut;