The Tri-State CheckBox mode of RadTreeView allows for Nodes' CheckBoxes (when enabled) to have an additional, third state - Indeterminate. A Node's CheckBox is in Indeterminatestate if it has both Checked and Unchecked CheckBoxes of child Nodes.
When RadTreeView is in Tri-State CheckBox mode, a Node's CheckBox can be in either of the following states:
Checked - CheckBoxes of all child Nodes are **Checked.
Unchecked - CheckBoxes of all child Nodes are Unchecked.
Indeterminate - there are Checked and Unchecked child Nodes' CheckBoxes.
A CheckBox in Tri-State-enabled TreeView goes through its states in the following order:
Checked -> Unchecked
Unchecked -> Checked
Indeterminate -> Checked
The Tri-State CheckBox mode of RadTreeView is enabled by setting the TriStateCheckBoxes property of the control to True. A prerequisite for this mode to work is to have enabled also CheckBoxes for Nodes.
An addition to the Tri-State CheckBox mode of RadTreeView is the "Check Child Nodes" functionality. When the CheckChildNodes property of RadTreeView is set to True and if:
A parent Node's CheckBox is checked then all child Nodes' CheckBoxes are also checked.
A parent Node's CheckBox is unchecked then all child Node's CheckBoxes are also unchecked.
The Indeterminate state of a Node is not persisted. That is if a Node's CheckBox is in Indeterminatestate and is unchecked, it can no longer return in the same Indeterminate state.