NIL is valid value for reading only. A run time error results, if an attempt is made to assign NIL to the :selReadOnly instance variable.
Member variable XbpRtf():selReadOnly Foundation
Specifies whether the text in the current selection can be edited by the user.
The :selReadOnly instance variables contains a logical value that specifies whether the user can modifiy the text currently selected in the XbpRtf object. If .F. (FALSE) is assigned to :selReadOnly, the text cannot be edited.
If the text in the current selection contains both readable and editable sections of text, the instance variable :selReadOnly contains the value NIL. This value represents an indeterminate state that the Xbase++ application may chose to visualize in its user interface. Some word processor applications use grayed controls to visualize conflicting properties in the current selection, for example.
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