tree control

Displays a logically hierarchical list of items in collapsible outline format. In Clarion, a small square filled with a plus or minus symbol, followed by a folder, represents an expandable tree control.


List boxes with a Tree modifier (T) have a Level field (a LONG) following the tree column. On initial display, if this Level is negative, the branch is contracted. (Note: if the line has no children and a negative level, it will show a [+] when it should not, so do not arbitrarily make every level negative, only do so for parent levels.)


As the user clicks the [+] [-] icons the tree is expanded and contracted. This does not change the Level sign but does post "expanded" and "contracted" events. On this event, you can manually update the level sign and save the contracted state of the tree.


To determine what row is currently selected, query the PROPLIST:MouseDownRow list box property.

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