TestEngine: revert part of 5b0510c as IMGUI_TEST_ENGINE_ITEM_ADD() woul see an erreneous hierarchy.

+ Fix typo (#5600)

imgui.cpp

@@ -6455,8 +6455,10 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
         if (g.TestEngineHookItems)
         {
             IM_ASSERT(window->IDStack.Size == 1);
+            window->IDStack.Size = 0; // As window->IDStack[0] == window->ID here, make sure TestEngine doesn't erroneously see window as parent of itself.
             IMGUI_TEST_ENGINE_ITEM_ADD(window->Rect(), window->ID);
             IMGUI_TEST_ENGINE_ITEM_INFO(window->ID, window->Name, (g.HoveredWindow == window) ? ImGuiItemStatusFlags_HoveredRect : 0);
+            window->IDStack.Size = 1;
         }
 #endif
 

imgui_internal.h

@@ -2165,7 +2165,7 @@ public:
     ImGuiID     GetID(int n);
     ImGuiID     GetIDFromRectangle(const ImRect& r_abs);
 
-    // We don't use g.FontSize because the window may be != g.CurrentWidow.
+    // We don't use g.FontSize because the window may be != g.CurrentWindow.
     ImRect      Rect() const            { return ImRect(Pos.x, Pos.y, Pos.x + Size.x, Pos.y + Size.y); }
     float       CalcFontSize() const    { ImGuiContext& g = *GImGui; float scale = g.FontBaseSize * FontWindowScale; if (ParentWindow) scale *= ParentWindow->FontWindowScale; return scale; }
     float       TitleBarHeight() const  { ImGuiContext& g = *GImGui; return (Flags & ImGuiWindowFlags_NoTitleBar) ? 0.0f : CalcFontSize() + g.Style.FramePadding.y * 2.0f; }