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Query: “TreeGrid - can I move the collapse/expand button (downward triangle) to the left side?”
In TreeGrid, expand/collapse icons are indented based on the level of the record (either parent or child) and not based on the width of the previous column content.
Please refer the below sample for better understanding,
But we have achieved your requirement (to render the icons without any indent both for parent and child records) by making changes in CSS. Kindly refer the below sample for your reference
Please get back to us if you have further queries.