Developed a pen thickness customization feature for the semicolon213/2024_GuestBook_T1 drawing tool, focusing on enhancing user control and editing precision. The work involved designing and implementing new GUI controls using C++ and the Windows API, allowing users to adjust and visualize pen thickness in real time. Integration with the existing color selection interface ensured a cohesive and intuitive user experience. The solution maintained visual consistency across the tool, aligning with the product’s roadmap for improved editing capabilities. This feature addressed the need for more precise drawing options, contributing to higher content quality and increased user satisfaction within the application.