For static widgets, this attribute is read-only and the handle accesses a literal widget containing the side label specified when the widget was defined. For dynamic widgets, you can set this handle to a text widget that you create as a side label. You first must create a dynamic text widget to use as a label (assign it a value, row, and column); then assign the handle of the text widget to the SIDE-LABEL-HANDLE attribute of the widget whose label you want to specify or change.