message: Make sure to apply the theme on load of the application
  Fixes
  _AplyTheme raises an event for the IslandWindow to handle and actually apply
  the theme, so we don't _really_ need to worry about it, but we do need to
  worry for ContentDialogs.
diff: @@ -110,6 +110,8 @@ namespace winrt::TerminalApp::implementation
  _OpenNewTab(std::nullopt);
  _tabContent.SizeChanged({ this, &App::_OnContentSizeChanged });
  +
  + _ApplyTheme(_settings->GlobalSettings().GetRequestedTheme());
  }
  App::~App()
  @@ -153,6 +155,11 @@ namespace winrt::TerminalApp::implementation
  // xaml tree somehow.
  dialog.XamlRoot(_root.XamlRoot());
  + // IMPORTANT: Set the requested theme of the dialog, because the
  + // PopupRoot isn't directly in the Xaml tree of our root. So the dialog
  + // won't inherit our RequestedTheme automagically.
  + dialog.RequestedTheme(_settings->GlobalSettings().GetRequestedTheme());
  +
  // Display the dialog.
  Controls::ContentDialogResult result = co_await dialog.ShowAsync(Controls::ContentDialogPlacement::Popup);
  @@ -740,7 +747,6 @@ namespace winrt::TerminalApp::implementation
  // - newTheme: The ElementTheme to apply to our elements.
  void App::_ApplyTheme(const Windows::UI::Xaml::ElementTheme& newTheme)
  {
  - _root.RequestedTheme(newTheme);
  // Propagate the event to the host layer, so it can update its own UI
  _requestedThemeChangedHandlers(*this, newTheme);
  }
  