From fa2e5710acbc55c16ef01c52c81b63bae895cf15 Mon Sep 17 00:00:00 2001
From: ocornut <omarcornut@gmail.com>
Date: Wed, 6 Sep 2023 12:39:39 +0200
Subject: [PATCH] MenuBar: Fixed an issue where layouting an item in the
 menu-bar would erroneously egister contents size. (#6789)

In dire need of removing BeginGroup()/EndGroup() from menu-bar code, fo r sanity.
---
 docs/CHANGELOG.txt |  3 +++
 imgui_internal.h   | 16 ++++++++--------
 imgui_widgets.cpp  | 10 ++++++++--
 3 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index 76feb98f..2717fc94 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt
@@ -47,6 +47,9 @@ Other changes:
 - InputTextMultiline: Fixed a crash pressing Down on last empty line of a multiline buffer.
   (regression from 1.89.2, only happened in some states). (#6783, #6000)
 - BeginListBox(): Fixed not consuming SetNextWindowXXX data when returning false.
+- MenuBar: Fixed an issue where layouting an item in the menu-bar would erroneously
+  register contents size in a way that would affect the scrolling layer.
+  Was most often noticable when using an horizontal scrollbar. (#6789)
 - Backends: GLFW: Clear emscripten's MouseWheel callback before shutdown. (#6790, #6096, #4019) [@halx99]
 
 
diff --git a/imgui_internal.h b/imgui_internal.h
index 7f6dbe35..65201ca6 100644
--- a/imgui_internal.h
+++ b/imgui_internal.h
@@ -1868,14 +1868,14 @@ struct ImGuiContext
     ImGuiNextWindowData     NextWindowData;                     // Storage for SetNextWindow** functions
 
     // Shared stacks
-    ImVector<ImGuiColorMod> ColorStack;                         // Stack for PushStyleColor()/PopStyleColor() - inherited by Begin()
-    ImVector<ImGuiStyleMod> StyleVarStack;                      // Stack for PushStyleVar()/PopStyleVar() - inherited by Begin()
-    ImVector<ImFont*>       FontStack;                          // Stack for PushFont()/PopFont() - inherited by Begin()
-    ImVector<ImGuiID>       FocusScopeStack;                    // Stack for PushFocusScope()/PopFocusScope() - inherited by BeginChild(), pushed into by Begin()
-    ImVector<ImGuiItemFlags>ItemFlagsStack;                     // Stack for PushItemFlag()/PopItemFlag() - inherited by Begin()
-    ImVector<ImGuiGroupData>GroupStack;                         // Stack for BeginGroup()/EndGroup() - not inherited by Begin()
-    ImVector<ImGuiPopupData>OpenPopupStack;                     // Which popups are open (persistent)
-    ImVector<ImGuiPopupData>BeginPopupStack;                    // Which level of BeginPopup() we are in (reset every frame)
+    ImVector<ImGuiColorMod>     ColorStack;                     // Stack for PushStyleColor()/PopStyleColor() - inherited by Begin()
+    ImVector<ImGuiStyleMod>     StyleVarStack;                  // Stack for PushStyleVar()/PopStyleVar() - inherited by Begin()
+    ImVector<ImFont*>           FontStack;                      // Stack for PushFont()/PopFont() - inherited by Begin()
+    ImVector<ImGuiID>           FocusScopeStack;                // Stack for PushFocusScope()/PopFocusScope() - inherited by BeginChild(), pushed into by Begin()
+    ImVector<ImGuiItemFlags>    ItemFlagsStack;                 // Stack for PushItemFlag()/PopItemFlag() - inherited by Begin()
+    ImVector<ImGuiGroupData>    GroupStack;                     // Stack for BeginGroup()/EndGroup() - not inherited by Begin()
+    ImVector<ImGuiPopupData>    OpenPopupStack;                 // Which popups are open (persistent)
+    ImVector<ImGuiPopupData>    BeginPopupStack;                // Which level of BeginPopup() we are in (reset every frame)
     ImVector<ImGuiNavTreeNodeData> NavTreeNodeStack;            // Stack for TreeNode() when a NavLeft requested is emitted.
 
     int                     BeginMenuCount;
diff --git a/imgui_widgets.cpp b/imgui_widgets.cpp
index d63a629f..e4ade8c7 100644
--- a/imgui_widgets.cpp
+++ b/imgui_widgets.cpp
@@ -7035,12 +7035,18 @@ void ImGui::EndMenuBar()
     PopClipRect();
     PopID();
     window->DC.MenuBarOffset.x = window->DC.CursorPos.x - window->Pos.x; // Save horizontal position so next append can reuse it. This is kinda equivalent to a per-layer CursorPos.
-    g.GroupStack.back().EmitItem = false;
-    EndGroup(); // Restore position on layer 0
+
+    // FIXME: Extremely confusing, cleanup by (a) working on WorkRect stack system (b) not using a Group confusingly here.
+    ImGuiGroupData& group_data = g.GroupStack.back();
+    group_data.EmitItem = false;
+    ImVec2 restore_cursor_max_pos = group_data.BackupCursorMaxPos;
+    window->DC.IdealMaxPos.x = ImMax(window->DC.IdealMaxPos.x, window->DC.CursorMaxPos.x - window->Scroll.x); // Convert ideal extents for scrolling layer equivalent.
+    EndGroup(); // Restore position on layer 0 // FIXME: Misleading to use a group for that backup/restore
     window->DC.LayoutType = ImGuiLayoutType_Vertical;
     window->DC.IsSameLine = false;
     window->DC.NavLayerCurrent = ImGuiNavLayer_Main;
     window->DC.MenuBarAppending = false;
+    window->DC.CursorMaxPos = restore_cursor_max_pos;
 }
 
 // Important: calling order matters!