Worked on the ex-em/EVUI repository to enhance the brush drag functionality across chart canvases, focusing on improving the user experience during data exploration. Leveraged JavaScript and advanced canvas manipulation to implement document-level mousemove and mouseup event handlers, allowing brush dragging to continue even when the cursor leaves the canvas area. Introduced an isDragMode flag to clearly distinguish between interaction modes, and applied boundary clamping to maintain visual integrity by preventing brush overflow. Reliability was further improved by adding guards against duplicate state initialization and migrating from canvas-leave logic to more robust document-level event handling, emphasizing maintainable front end development.