The rows property is used to control how many rows are visible. By setting it to zero, the tree control will resize itself to hold as many as items if possible.
The checkmark property controls whether to display a checkbox or a radio button in front of each tree item.
The vflex property controls whether to grow and shrink vertical to fit their given space. It is so-called vertical flexibility. For example, if the tree is too big to fit in the browser window, it will shrink the height to make the whole tree visible in the browser window.
This property is ignored if the rows property is specified.
The maxlength property defines the maximal allowed characters being visible at the browser. By setting this property, you could make a narrower tree control.