AnyChart JavaScript Gantt Chart lets you customize data grid collapse and expand buttons with vector-drawn shapes for a fully custom look.
This sample creates a project Gantt chart and replaces the default data-grid buttons with triangle icons rendered through the graphics vector primitives API. The normal state draws a right-pointing blue triangle, and the selected (expanded) state draws a down-pointing dark triangle. Button backgrounds are disabled so only the drawn shapes are visible. The chart starts fully collapsed and programmatically expands the "pre-planning" task to demonstrate both button states.
See the Gantt Chart documentation for all configuration options.