XClientMessageEvent - ColormapNotify event structure
The structure for ClientMessage events contains:
typedef struct {
int type; ClientMessage
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 window;
Atom message_type;
int format;
union {
char b[20];
short s[10];
long l[5];
} data;
} XClientMessageEvent;