gtk:widget-add-css-class (widget class)

widget -- a gtk:widget object
class -- a string for the style class to add, without the leading "." used for notation of style classes

Adds class to the widget. After calling this function, the style of the widget will match for class, after the CSS matching rules. Get the CSS style classes, add and remove a CSS style class:

(defvar dialog (make-instance 'gtk:about-dialog)) => DIALOG
(gtk:widget-css-classes dialog)
=> ("background" "csd" "aboutdialog")
(gtk:widget-add-css-class dialog "mystyle")
(gtk:widget-css-classes dialog)
=> ("background" "csd" "aboutdialog" "mystyle")
(gtk:widget-remove-css-class dialog "mystyle")
(gtk:widget-css-classes dialog)
=> ("background" "csd" "aboutdialog")