To maintain compatibility while modernizing a legacy GUI:

1. Gradual updates: Update components incrementally to avoid disrupting existing functionality.

2. Compatibility testing: Thoroughly test new components with existing infrastructure.

3. API abstraction: Use APIs to abstract modernized components from legacy code.

4. Wrapper components: Create wrapper components to integrate new GUI elements with legacy code.

5. Emulation: Emulate legacy GUI behavior in modernized components.

6. Dual-runtime support: Support both legacy and modernized GUI components simultaneously.

7. Feature toggles: Use feature toggles to switch between legacy and modernized components.

8. Legacy mode: Provide a "legacy mode" to maintain compatibility with older systems.

9. Documentation: Maintain detailed documentation of changes and updates.

10. User feedback: Collect user feedback to identify and address compatibility issues.

11. Automated testing: Use automated testing to ensure compatibility and functionality.

12. Version control: Manage different versions of the GUI and legacy system.

By following these strategies, you can modernize a legacy GUI while maintaining compatibility with existing infrastructure, ensuring a seamless transition for users.