From Xojo Documentation
| This item was deprecated in version 2019r2.
Please use CheckBox.VisualStates as a replacement.
The CheckedStates enum has the following values:
To get the state, read the value of the State property. For example,
Setting the State automatically updates the CheckBox's Value property.
A Checkbox cell in a ListBox is managed via the CellState method. You assign a value using the CheckedStates enum. For example, the following code checks the cell's checkbox.