From a528398c7780647d8a7d3bc46593dec987e76a1f Mon Sep 17 00:00:00 2001
From: ocornut <omarcornut@gmail.com>
Date: Tue, 14 Dec 2021 16:17:31 +0100
Subject: [PATCH] Internals: support for varying _ChildWindow flag for menu
 windows. (#3496, #4797)

---
 imgui.cpp | 31 +++++++++++++++++++++++++------
 imgui.h   |  2 +-
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/imgui.cpp b/imgui.cpp
index 99c8f0d9ce9a..39917cdb194b 100644
--- a/imgui.cpp
+++ b/imgui.cpp
@@ -5286,6 +5286,27 @@ static void ApplyWindowSettings(ImGuiWindow* window, ImGuiWindowSettings* settin
     window->Collapsed = settings->Collapsed;
 }
 
+static void UpdateWindowInFocusOrderList(ImGuiWindow* window, bool just_created, ImGuiWindowFlags new_flags)
+{
+    ImGuiContext& g = *GImGui;
+    const ImGuiWindowFlags old_flags = window->Flags;
+    const bool child_flag_changed = (new_flags & ImGuiWindowFlags_ChildWindow) != (old_flags & ImGuiWindowFlags_ChildWindow);
+
+    if ((just_created || child_flag_changed) && !(new_flags & ImGuiWindowFlags_ChildWindow))
+    {
+        g.WindowsFocusOrder.push_back(window);
+        window->FocusOrder = (short)(g.WindowsFocusOrder.Size - 1);
+    }
+    else if (child_flag_changed && (new_flags & ImGuiWindowFlags_ChildWindow))
+    {
+        IM_ASSERT(g.WindowsFocusOrder[window->FocusOrder] == window);
+        for (int n = window->FocusOrder + 1; n < g.WindowsFocusOrder.Size; n++)
+            g.WindowsFocusOrder[n]->FocusOrder--;
+        g.WindowsFocusOrder.erase(g.WindowsFocusOrder.Data + window->FocusOrder);
+        window->FocusOrder = -1;
+    }
+}
+
 static ImGuiWindow* CreateNewWindow(const char* name, ImGuiWindowFlags flags)
 {
     ImGuiContext& g = *GImGui;
@@ -5325,16 +5346,12 @@ static ImGuiWindow* CreateNewWindow(const char* name, ImGuiWindowFlags flags)
         window->AutoFitOnlyGrows = (window->AutoFitFramesX > 0) || (window->AutoFitFramesY > 0);
     }
 
-    if (!(flags & ImGuiWindowFlags_ChildWindow))
-    {
-        g.WindowsFocusOrder.push_back(window);
-        window->FocusOrder = (short)(g.WindowsFocusOrder.Size - 1);
-    }
-
     if (flags & ImGuiWindowFlags_NoBringToFrontOnFocus)
         g.Windows.push_front(window); // Quite slow but rare and only once
     else
         g.Windows.push_back(window);
+    UpdateWindowInFocusOrderList(window, true, window->Flags);
+
     return window;
 }
 
@@ -5934,6 +5951,8 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
     const bool window_just_created = (window == NULL);
     if (window_just_created)
         window = CreateNewWindow(name, flags);
+    else
+        UpdateWindowInFocusOrderList(window, window_just_created, flags);
 
     // Automatically disable manual moving/resizing when NoInputs is set
     if ((flags & ImGuiWindowFlags_NoInputs) == ImGuiWindowFlags_NoInputs)
diff --git a/imgui.h b/imgui.h
index 4d0ecaa1db57..733752950c00 100644
--- a/imgui.h
+++ b/imgui.h
@@ -64,7 +64,7 @@ Index of this file:
 // Version
 // (Integer encoded as XYYZZ for use in #if preprocessor conditionals. Work in progress versions typically starts at XYY99 then bounce up to XYY00, XYY01 etc. when release tagging happens)
 #define IMGUI_VERSION               "1.86 WIP"
-#define IMGUI_VERSION_NUM           18519
+#define IMGUI_VERSION_NUM           18520
 #define IMGUI_CHECKVERSION()        ImGui::DebugCheckVersionAndDataLayout(IMGUI_VERSION, sizeof(ImGuiIO), sizeof(ImGuiStyle), sizeof(ImVec2), sizeof(ImVec4), sizeof(ImDrawVert), sizeof(ImDrawIdx))
 #define IMGUI_HAS_TABLE