t. This argument is deprecated.
If there is a current selection in the pane, then the attributes are those set for the selected text. If there is no selection, then it gets the "typing attributes", which are applied to characters that are typed by the user. Note that any cursor movement changes these attributes, so their values are ephemeral.
t if all the selection is bold.
nil if all the selection is not bold.
:unknown if the selection is only partially bold.
For the possible attributes, see set-rich-text-pane-character-format.
nil for the keyword argument
:selection is not supported in LispWorks 6.1 and later. See the description above for details of the current behavior with respect to the current selection in the rich-text-pane.
CAPI User Guide and Reference Manual (Macintosh version) - 25 Feb 2015