proper game mode detection

apps/openmw/mwgui/keyboardnavigation.cpp

@@ -116,8 +116,7 @@ void KeyboardNavigation::onFrame()
     if (!mEnabled)
         return;
 
-    MWGui::GuiMode mode = MWBase::Environment::get().getWindowManager()->getMode();
-    if (mode == GM_None)
+    if (!MWBase::Environment::get().getWindowManager()->isGuiMode())
     {
         MWBase::Environment::get().getWindowManager()->setKeyFocusWidget(nullptr);
         return;
@@ -222,8 +221,7 @@ bool KeyboardNavigation::injectKeyPress(MyGUI::KeyCode key, unsigned int text, b
 
 bool KeyboardNavigation::switchFocus(int direction, bool wrap)
 {
-    MWGui::GuiMode mode = MWBase::Environment::get().getWindowManager()->getMode();
-    if (mode == GM_None)
+    if (!MWBase::Environment::get().getWindowManager()->isGuiMode())
         return false;
 
     MyGUI::Widget* focus = MyGUI::InputManager::getInstance().getKeyFocusWidget();