fix imgui pivot bug

deps/imgui/imgui.cpp

@@ -5684,7 +5684,7 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
 
         const bool window_pos_with_pivot = (window->SetWindowPosVal.x != FLT_MAX && window->HiddenFramesCannotSkipItems == 0);
         if (window_pos_with_pivot)
-            SetWindowPos(window, window->SetWindowPosVal - window->SizeFull * window->SetWindowPosPivot, 0); // Position given a pivot (e.g. for centering)
+            SetWindowPos(window, window->SetWindowPosVal - window->Size * window->SetWindowPosPivot, 0); // Position given a pivot (e.g. for centering)
         else if ((flags & ImGuiWindowFlags_ChildMenu) != 0)
             window->Pos = FindBestWindowPosForPopup(window);
         else if ((flags & ImGuiWindowFlags_Popup) != 0 && !window_pos_set_by_api && window_just_appearing_after_hidden_for_resize)