The coldef clause ScrollMode=Tree may be used in conjunction with combo boxes (List=) to cause ordinary Up/DownArrows to move the focus to the previous/next row, rather than to the previous/next item in the list. In other words, it causes ordinary Up/DownArrows to act the same as Ctrl+Up/DownArrows. It also affects ordinary Left/RightArrows in selection-only combo boxes (where they normally act just like up/down).

The intent of this obscure (and somewhat non-standard) 'feature' is mainly to minimize the possibility that users might accidentally change cell values when they were intending to just "arrow around" the grid. (This is much more likely within XTREE, where ordinary cells may turn into combo boxes when they get the focus, than with "normal" combo boxes that may appear in dialogs.

Note that in all cases, when the drop-down list is displayed (via Alt+DownArrow or clicking on the drop-down button), the arrow keys will operate within the list (so it doesn't interfere with the ability to perform all the necessary combo box functions without using the mouse).

The Mouse Wheel operation is similarly affected by the ScrollMode=Tree clause.

As of 5.1.1174, ScrollMode=Tree also affects the operation of XTF_UP and XTF2_DOWN (affecting both editable and non-editable contexts).

Once a ScrollMode command is encountered in the coldef string, it becomes the default for any editable columns subsequently defined. The last encountered ScrollMode statement will determine the behavior in non-column-specific contexts (such as in using the Up/DownArrows in non-editable contexts).

ScrollMode=Tree may be associated with column 0 to make it the default for all columns (rather than having to do it individually for each column containing combos).