Cross-Platform Desktop App Development

I need a skilled software engineer to develop a cross-platform desktop application that runs on Windows, MacOS, and Linux.

Key Requirements:
- Experience in building desktop applications
- Proficiency in cross-platform development tools and frameworks
- Strong knowledge of Windows, MacOS, and Linux environments

Ideal skills and experience:
- Expertise in languages like C++, Java, or Python
- Familiarity with UI/UX design for desktop apps
- Background in software testing and debugging across multiple OS

Please provide a detailed portfolio with relevant projects.