https://www.screencast.com/t/UgqUZbqenpj5
The ItemDataBound event does not cause unnecessary data binding, it would fire for each data bound item anyway.
Please fix this bug asap, as in my project i am generating all dropdowns dynamically and its not good to have databind all the time unnecessary.
A workaround is trimming the items in the ItemDataBound event of the DropDownList: protected void CategoryIDDropDown_ItemDataBound(object sender, DropDownListItemEventArgs e) { e.Item.Text = e.Item.Text.Trim(); }