Multi-row selection and tree-views

Multi-row selection can be used with a DISPLAY ARRAY controlling a TREE container.

Due to the tree-view ergonomic differences with simple tables, the selection of tree nodes follows some specific rules, compared to multiple-row selection in simple tables:

1. When selecting a range of nodes, only visible nodes will get the selection flag. For example, if you select all nodes with Ctrl-A, and if the root node is collapsed, only the root node will be selected. This applies also when selecting nodes by program with the DIALOG.setSelectionRange().
2. Collapsing a node will deselect all child nodes.