https://invisible-island.net/xterm/xtoolkit/
XtNextEvent, XtPending, XtPeekEvent, XtProcessEvent, XtMainLoop - query and process events and input
#include <X11/Intrinsic.h> void XtNextEvent(XEvent *event_return); Boolean XtPeekEvent(XEvent *event_return); Boolean XtPending(void); void XtProcessEvent(XtInputMask mask); void XtMainLoop(void);
event Specifies a pointer to the event structure that is to be dis- patched to the appropriate event handler. event_return Returns the event information to the specified event struc- ture. mask Specifies what types of events to process. The mask is the bitwise inclusive OR of any combination of XtIMXEvent, XtIM- Timer, XtIMAlternateInput, and XtIMSignal. As a convenience, the X Toolkit defines the symbolic name XtIMAll to be the bitwise inclusive OR of all event types.
XtNextEvent has been replaced by XtAppNextEvent. XtPeekEvent has been replaced by XtAppPeekEvent. XtPending has been replaced by XtAppPending. XtProcessEvent has been replaced by XtAppProcessEvent. XtMainLoop has been replaced by XtAppMainLoop.
XtAppNextEvent(3xt), XtAppPending(3), XtAppPeekEvent(3), XtAppProces- sEvent(3), XtAppMainLoop(3) X Toolkit Intrinsics – C Language Interface Xlib - C Language X Interface X Version 11 libXt 1.1.5.2 XtNextEvent(3)