fix rendersystem selection

Author: paroj

ogre_mesh_viewer.py

@@ -140,7 +140,7 @@ def draw_render_settings(self):
         flags = ImGui.WindowFlags_AlwaysAutoResize
         self.show_render_settings = ImGui.Begin("Renderer Settings", self.show_render_settings, flags)[1]
 
-        Ogre.Overlay.DrawRenderingSettings(app.next_rendersystem)
+        app.next_rendersystem = Ogre.Overlay.DrawRenderingSettings(app.next_rendersystem)
 
         ImGui.Separator()