Supporting setting panel layout

engine/src/ui/panels/panel_registry_panel.cpp

@@ -5,7 +5,6 @@
 namespace sophia {
 
 void PanelRegistryPanel::onUpdate(const FrameInfo&) {
-  ImGui::Begin("PanelRegistry");
   ImGui::Text("%u panels (%u visible)", registry.size(),
               registry.visibleCount());
   ImGui::Separator();
@@ -21,8 +20,6 @@ void PanelRegistryPanel::onUpdate(const FrameInfo&) {
       panel->setVisible(visible);
     }
   }
-
-  ImGui::End();
 }
 
 }  // namespace sophia