Docking: Fix DockBuilderAddNode() not storing flags when creating floating node.

imgui.cpp

@@ -13070,6 +13070,7 @@ ImGuiID ImGui::DockBuilderAddNode(ImGuiID id, ImGuiDockNodeFlags flags)
             node = DockContextFindNodeByID(ctx, id);
         if (!node)
             node = DockContextAddNode(ctx, id);
+        node->Flags = flags;
     }
     node->LastFrameAlive = ctx->FrameCount;   // Set this otherwise BeginDocked will undock during the same frame.
     return node->ID;