[ Flags ]
public enum ModifierType
Flags to indicate the state of modifier keys and mouse buttons in events.
Typical modifier keys are Shift, Control, Meta, Super, Hyper, Alt, Compose, Apple, CapsLock or ShiftLock.
Note that GDK may add internal values to events which include values outside of this enumeration. Your code should preserve and ignore them. You can use gdk_modifier_mask to remove all private values.