Fixed Columns
The Tree List allows columns to be anchored to the left or right edge. When the column is anchored, its content isn’t horizontally scrolled. Such columns are called - fixed columns.
To make a column fixed, use its TreeListColumn.Fixed property. To anchor the column to the Tree List’s left edge, set this property to FixedStyle.Left. To anchor the columns to the right edge, set the TreeListColumn.Fixed property to FixedStyle.Right. Fixed columns are separated from others by vertical lines whose width is specified by the TreeList.FixedLineWidth property.
Note
Using the Fixed Columns feature makes sense only if the Auto Width feature is disabled (the TreeListOptionsView.AutoWidth property is set to false), and the total width of columns exceeds the Tree List’s width.