Class ExampleTreeFuncs

imgui_tiny_app/imgui/imgui_demo.cpp:3154–3259

                "Future versions will try to simplify and formalize some of this.");

            struct ExampleTreeFuncs
            {
                static void DrawNode(ExampleTreeNode* node, ImGuiSelectionBasicStorage* selection)
                {
                    ImGuiTreeNodeFlags tree_node_flags = ImGuiTreeNodeFlags_SpanAvailWidth | ImGuiTreeNodeFlags_OpenOnArrow | ImGuiTreeNodeFlags_OpenOnDoubleClick;
                    tree_node_flags |= ImGuiTreeNodeFlags_NavLeftJumpsToParent; // Enable pressing left to jump to parent
                    if (node->Childs.Size == 0)
                        tree_node_flags |= ImGuiTreeNodeFlags_Bullet | ImGuiTreeNodeFlags_Leaf;
                    if (selection->Contains((ImGuiID)node->UID))
                        tree_node_flags |= ImGuiTreeNodeFlags_Selected;

                    // Using SetNextItemStorageID() to specify storage id, so we can easily peek into
                    // the storage holding open/close stage, using our TreeNodeGetOpen/TreeNodeSetOpen() functions.
                    ImGui::SetNextItemSelectionUserData((ImGuiSelectionUserData)(intptr_t)node);
                    ImGui::SetNextItemStorageID((ImGuiID)node->UID);
                    if (ImGui::TreeNodeEx(node->Name, tree_node_flags))
                    {
                        for (ExampleTreeNode* child : node->Childs)
                            DrawNode(child, selection);
                        ImGui::TreePop();
                    }
                    else if (ImGui::IsItemToggledOpen())
                    {
                        TreeCloseAndUnselectChildNodes(node, selection);
                    }
                }

                // When closing a node: 1) close and unselect all child nodes, 2) select parent if any child was selected.
                // FIXME: This is currently handled by user logic but I'm hoping to eventually provide tree node
                // features to do this automatically, e.g. a ImGuiTreeNodeFlags_AutoCloseChildNodes etc.
                static int TreeCloseAndUnselectChildNodes(ExampleTreeNode* node, ImGuiSelectionBasicStorage* selection, int depth = 0)
                {
                    // Recursive close (the test for depth == 0 is because we call this on a node that was just closed!)
                    int unselected_count = selection->Contains((ImGuiID)node->UID) ? 1 : 0;
                    if (depth == 0 || ImGui::TreeNodeGetOpen((ImGuiID)node->UID))
                    {
                        for (ExampleTreeNode* child : node->Childs)
                            unselected_count += TreeCloseAndUnselectChildNodes(child, selection, depth + 1);
                        ImGui::TreeNodeSetOpen((ImGuiID)node->UID, false);
                    }

                    // Select root node if any of its child was selected, otherwise unselect
                    selection->SetItemSelected((ImGuiID)node->UID, (depth == 0 && unselected_count > 0));
                    return unselected_count;
                }

                // Apply multi-selection requests
                static void ApplySelectionRequests(ImGuiMultiSelectIO* ms_io, ExampleTreeNode* tree, ImGuiSelectionBasicStorage* selection)
                {
                    for (ImGuiSelectionRequest& req : ms_io->Requests)
                    {
                        if (req.Type == ImGuiSelectionRequestType_SetAll)
                        {
                            if (req.Selected)
                                TreeSetAllInOpenNodes(tree, selection, req.Selected);
                            else
                                selection->Clear();
                        }