Reading this attribute will return the number of
the active entry (the one with the cursor on it).
The result is between 0 and Listview.Entries-1
or Off, in which case there is currently no active
entry.
Setting the attribute will cause the list to
move the cursor to the new position and scroll
this position into the visible area.
The following special values are possible when setting
this attribute:
Off-
Clear selection.
Top-
Select top entry.
Bottom-
Select bottom entry.
Up-
Select previous entry.
Down-
Select next entry.
PageUp-
Move list cursor one page up.
PageDown-
Move list cursor one page down.