Revert 640c0566: TreeNode: Fixed nodes with ImGuiTreeNodeFlags_Leaf flag always returning true which was meaningless -> more flexible to keep allowing it by default so it setup an ID scope.

imgui.cpp

@@ -8323,7 +8323,7 @@ void ImGui::LogButtons()
 bool ImGui::TreeNodeBehaviorIsOpen(ImGuiID id, ImGuiTreeNodeFlags flags)
 {
     if (flags & ImGuiTreeNodeFlags_Leaf)
-        return false;
+        return true;
 
     // We only write to the tree storage if the user clicks (or explicitly use SetNextTreeNode*** functions)
     ImGuiContext& g = *GImGui;