Fix for border under title bar when WindowBorderSize == 0 and FrameBorderSize > 0

imgui.cpp

@@ -4766,7 +4766,7 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
                 window->DrawList->AddLine(border.Min, border.Max, GetColorU32(ImGuiCol_SeparatorActive), ImMax(1.0f, window_border_size));
             }
             if (style.FrameBorderSize > 0 && !(flags & ImGuiWindowFlags_NoTitleBar))
-                window->DrawList->AddLine(title_bar_rect.GetBL()+ImVec2(1,-1), title_bar_rect.GetBR()+ImVec2(-1,-1), GetColorU32(ImGuiCol_Border), style.FrameBorderSize);
+                window->DrawList->AddLine(title_bar_rect.GetBL() + ImVec2(style.WindowBorderSize, -1), title_bar_rect.GetBR() + ImVec2(-style.WindowBorderSize,-1), GetColorU32(ImGuiCol_Border), style.FrameBorderSize);
         }
 
         // Store a backup of SizeFull which we will use next frame to decide if we need scrollbars.