From 1575a3fbcdcea3ea85639cf098c7909f33270cae Mon Sep 17 00:00:00 2001
From: omar <omarcornut@gmail.com>
Date: Sun, 19 May 2019 17:00:17 +0200
Subject: [PATCH] Docking: Fixed temporarily losing Dockspace flag when merging
 remaining sibling back into a parent node. (#2563, #2109) Would trigger an
 assert in the Passthru hole path. Broken by fd5859ed.

---
 imgui.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/imgui.cpp b/imgui.cpp
index e64b6d33..2d1e0d2a 100644
--- a/imgui.cpp
+++ b/imgui.cpp
@@ -12929,7 +12929,9 @@ void ImGui::DockNodeTreeMerge(ImGuiContext* ctx, ImGuiDockNode* parent_node, ImG
     parent_node->SizeRef = backup_last_explicit_size;
 
     // Flags transfer
-    parent_node->LocalFlags = ((child_0 ? child_0->LocalFlags : 0) | (child_1 ? child_1->LocalFlags : 0)) & ImGuiDockNodeFlags_LocalFlagsTransferMask_;
+    parent_node->LocalFlags &= ~ImGuiDockNodeFlags_LocalFlagsTransferMask_; // Preserve Dockspace flag
+    parent_node->LocalFlags |= (child_0 ? child_0->LocalFlags : 0) & ImGuiDockNodeFlags_LocalFlagsTransferMask_;
+    parent_node->LocalFlags |= (child_1 ? child_1->LocalFlags : 0) & ImGuiDockNodeFlags_LocalFlagsTransferMask_;
 
     if (child_0)
     {