To receive ReparentNotify events, set the StructureNotifyMask bit in the event-mask attribute of the window or the SubstructureNotifyMask bit in the event-mask attribute of either the old or the new parent window (in which case, reparenting any child generates an event).
The structure for this event type contains:
typedef struct {
int type; /* ReparentNotify */
unsigned long serial; /* # of last request processed by server */
Bool send_event; /* true if this came from a SendEvent request */
Display *display; /* Display the event was read from */
Window event;
Window window;
Window parent;
int x, y;
Bool override_redirect;
} XReparentEvent;
The event member is set either to the reparented window or to the old or the new parent, depending on whether StructureNotify or SubstructureNotify was selected.
The window member is set to the window that was reparented. The parent member is set to the new parent window.
The x and y members are set to the reparented window's coordinates relative to the new parent window's origin and define the upper-left outer corner of the reparented window.
The override_redirect member is set to the override-redirect attribute of the window specified by the window member. Window manager clients normally should ignore this window if the override_redirect member is True.