message: Horizontal layout does the minimum job to be usable internally - not exposed
diff: @@ -1922,6 +1922,10 @@ void ImGui::ItemSize(const ImVec2& size, float text_offset_y)
  window->DC.PrevLineHeight = line_height;
  window->DC.PrevLineTextBaseOffset = text_base_offset;
  window->DC.CurrentLineHeight = window->DC.CurrentLineTextBaseOffset = 0.0f;
  +
  + // Horizontal layout mode
  + if (window->DC.LayoutType == ImGuiLayoutType_Horizontal)
  + SameLine();
  }
  void ImGui::ItemSize(const ImRect& bb, float text_offset_y)
  @@ -9062,8 +9066,7 @@ bool ImGui::BeginMenu(const char* label, bool enabled)
  float w = label_size.x;
  pressed = Selectable(label, menu_is_open, ImGuiSelectableFlags_Menu | ImGuiSelectableFlags_DontClosePopups | (!enabled ? ImGuiSelectableFlags_Disabled : 0), ImVec2(w, 0.0f));
  PopStyleVar();
  - SameLine();
  - window->DC.CursorPos.x += (float)(int)(style.ItemSpacing.x * 0.5f);
  + window->DC.CursorPos.x += (float)(int)(style.ItemSpacing.x * (-1.0f + 0.5f)); // -1 spacing to compensate the spacing added when Selectable() did a SameLine(). It would also work to call SameLine() ourselves after the PopStyleVar().
  }
  else
  {
  @@ -10053,10 +10056,15 @@ void ImGui::NewLine()
  ImGuiWindow* window = GetCurrentWindow();
  if (window->SkipItems)
  return;
  +
  + ImGuiContext& g = *GImGui;
  + const ImGuiLayoutType backup_layout_type = window->DC.LayoutType;
  + window->DC.LayoutType = ImGuiLayoutType_Vertical;
  if (window->DC.CurrentLineHeight > 0.0f) // In the event that we are on a line with items that is smaller that FontSize high, we will preserve its height.
  ItemSize(ImVec2(0,0));
  else
  - ItemSize(ImVec2(0.0f, GImGui->FontSize));
  + ItemSize(ImVec2(0.0f, g.FontSize));
  + window->DC.LayoutType = backup_layout_type;
  }
  void ImGui::NextColumn()
  