gtk:drop-down-expression (object)

object -- a gtk:drop-down widget
expression -- a gtk:expression object, or the NULL pointer

The accessor for the expression slot of the gtk:drop-down class gets or sets the expression that gets evaluated to obtain strings from items when searching in the popup. The expression must have a value of "gchararray" type. The expression is represented as a foreign pointer. Use the (cffi:null-pointer) function to retrieve the NULL pointer representation.