These properties define the state of "Default" checkbox in the dialog.
property DefaultChecked: Boolean;
property DefaultPersistent: Boolean
If "Default" checkbox is checked, when properties are applied, they are assigned to "insert table" and "insert horizontal line" action as well, so they become default properties for new tables / lines.
DefaultChecked specifies the initial value of this checkbox (when the form is shown).
if DefaultPersistent = True, when the user pressed "OK" in the dialog, DefaultChecked property is updated according to the checkbox state (so it will have the same state when the dialog will be shown next time).