Demo: Commented out ideas on another way to center a window.

imgui_demo.cpp

@@ -2923,8 +2923,11 @@ static void ShowDemoWindowPopups()
             ImGui::OpenPopup("Delete?");
 
         // Always center this window when appearing
-        ImGuiViewport* viewport = ImGui::GetMainViewport();
-        ImGui::SetNextWindowPos(viewport->GetCenter(), ImGuiCond_Appearing, ImVec2(0.5f, 0.5f));
+        ImVec2 center = ImGui::GetMainViewport()->GetCenter();
+        //ImVec2 parent_pos = ImGui::GetWindowPos();
+        //ImVec2 parent_size = ImGui::GetWindowSize();
+        //ImVec2 center(parent_pos.x + parent_size.x * 0.5f, parent_pos.y + parent_size.y * 0.5f);
+        ImGui::SetNextWindowPos(center, ImGuiCond_Appearing, ImVec2(0.5f, 0.5f));
 
         if (ImGui::BeginPopupModal("Delete?", NULL, ImGuiWindowFlags_AlwaysAutoResize))
         {