Use first resolution in fullscreen if current is not supported (Fixes #4113)

apps/openmw/mwgui/settingswindow.cpp

@@ -353,24 +353,31 @@ namespace MWGui
             }
 
             bool supported = false;
+            int fallbackX = 0, fallbackY = 0;
             for (unsigned int i=0; i<mResolutionList->getItemCount(); ++i)
             {
                 std::string resStr = mResolutionList->getItemNameAt(i);
                 int resX, resY;
                 parseResolution (resX, resY, resStr);
 
+                if (i == 0)
+                {
+                    fallbackX = resX;
+                    fallbackY = resY;
+                }
+
                 if (resX == Settings::Manager::getInt("resolution x", "Video")
                     && resY  == Settings::Manager::getInt("resolution y", "Video"))
                     supported = true;
             }
 
-            if (!supported)
+            if (!supported && mResolutionList->getItemCount())
             {
-                std::string msg = "This resolution is not supported in Fullscreen mode. Please select a resolution from the list.";
-                MWBase::Environment::get().getWindowManager()->
-                    messageBox(msg);
-                _sender->castType<MyGUI::Button>()->setCaption(off);
-                return;
+                if (fallbackX != 0 && fallbackY != 0)
+                {
+                    Settings::Manager::setInt("resolution x", "Video", fallbackX);
+                    Settings::Manager::setInt("resolution y", "Video", fallbackY);
+                }
             }
 
             mWindowBorderButton->setEnabled(!newState);