The different types of testing applicable to GUI applications are:

1. Unit Testing: Testing individual components or functions.

2. Integration Testing: Testing how components interact with each other.

3. System Testing: Testing the entire application as a whole.

4. Acceptance Testing: Testing to ensure the application meets requirements.

5. Usability Testing: Testing user experience and interface usability.

6. Compatibility Testing: Testing across different devices, browsers, and OS.

7. Performance Testing: Testing application speed, scalability, and responsiveness.

8. Security Testing: Testing for vulnerabilities and security threats.

9. Regression Testing: Testing changes don't break existing functionality.

10. Exploratory Testing: Testing without preconceived test cases.

11. User Interface (UI) Testing: Testing visual elements and layout.

12. User Experience (UX) Testing: Testing overall user experience.

13. Accessibility Testing: Testing for accessibility and inclusivity.

14. Localization Testing: Testing for language and cultural adaptability.

15. Compatibility Testing with Assistive Technologies: Testing with screen readers, etc.

By conducting these types of testing, you can ensure your GUI application is stable, secure, user-friendly, and meets the required standards.