The CellTips property determines whether the list displays a pop-up text window when the cursor is idle. By default, this property is set to NoCellTips, and cell tips are not displayed.

If the CellTips property is set to either Anchored or Floating, the C1.Win.List.ListBase.C1ListBase.FetchCellTips event will be fired whenever the list has focus and the cursor is idle over a list cell, record selector, column header, split header, or list caption. The event will not fire if the cursor is over the scroll bars.

The setting Anchored aligns the cell tip window with either the left or right edge of the cell. The left edge is favored, but the right edge will be used if necessary in order to display as much text as possible.

The setting Floating displays the cell tip window below the cursor, if possible.

If you do not provide a handler for the FetchCellTips event, and the cursor is over a list cell, the default behavior is to display a text box containing the cell's contents (up to 256 characters). This enables the user to peruse the contents of a cell even if it is not big enough to be displayed in its entirety. You can also program the FetchCellTips event to override the default cell text display in order to provide users with context-sensitive help.

Reference

DropDownList Class
DropDownList Members