gtk:entry-max-length (object)

object -- a gtk:entry widget
max -- an integer for the maximum length of the text entry, or 0 for no maximum, the value passed in will be clamped to the range [0, 65536]

The accessor for the max-length slot gets or sets the maximum allowed length of the text in the text entry. If the current contents are longer than the given length, then they will be truncated to fit. This function is equivalent to

(gtk:entry-buffer-max-length (gtk:entry-buffer object))    

and

(setf (gtk:entry-buffer-max-length (gtk:entry-buffer object)) max)