Leo Defossez enhanced the MooseIDE repository by delivering targeted improvements to entity filtering and user interface reliability. He refactored the QueriesBrowser to utilize TEntityMetaLevelDependency for entity filtering, replacing the previous TNamedEntity approach to achieve greater precision and performance in entity selection. Additionally, Leo addressed a UI issue by correcting the properties pane extension management, ensuring accurate show and hide behavior for extensions. His work demonstrated proficiency in IDE development, metamodel management, and refactoring using Smalltalk. These changes contributed to a more stable and efficient developer workflow, reducing debugging time and improving the overall reliability of MooseIDE.