While the Tree class manages the relationship of the tree nodes, the TreeviewField object displays a visual representation of the hierarchical structure of a tree view. The TreeviewField class has an attribute of type Tree. Initially, the tree is empty. You can use the AddNode method of the Tree class to insert nodes into the tree.

Each TreeNode is displayed with its text label and optionally a bitmap. The TreeviewField can also display outlines to emphasize the structure of the nodes. Additionally, a parent node can have expansion buttons with the [+] and [-] symbols to indicate its expanded and collapsed states. Nodes can also display check boxes.

The TreeviewField scrolls during a drag-and-drop operation if the mouse pointer is on the first or last visible node.

Each TreeNode can have a pair of bitmap labels to indicate its selected or unselected states. The ImageList attribute of the TreeviewField object is an array of BitmapObject objects. You use the BmpLblIndx attribute and SelBmpLblIndx attribute of the TreeNode class to specify which images in the array are to be displayed for the node. By default, the first image is used for both selected and unselected states. The bitmaps are resized if necessary and displayed in a 16-pixel by 16-pixel dimension.

The keyboard can be used to navigate the tree. The up arrow and down arrow keys move through expanded nodes. The left arrow key and the minus key on the numeric keypad collapse parent nodes, while the right arrow key and the plus key on the numeric keypad expand them. The Home key moves to the root node. The End key moves to the last node. The PageUp and PageDn keys scroll through the tree.