Document that it is best to explicitly set width-chars and
max-width-chars to avoid surprises.
https://bugzilla.gnome.org/show_bug.cgi?id=727294
*
* The main properties of a GtkSpinButton are through an adjustment.
* See the #GtkAdjustment section for more details about an adjustment's
- * properties.
+ * properties. Note that GtkSpinButton will by default make its entry
+ * large enough to accomodate the lower and upper bounds of the adjustment,
+ * which can lead to surprising results. Best practice is to set both
+ * the #GtkEntry::width-chars and #GtkEntry::max-width-chars poperties
+ * to the desired number of characters to display in the entry.
*
* # CSS nodes
*