XtAppAddBlockHook man page
XtAppAddBlockHook, XtRemoveBlockHook — register a block hook procedure
XtBlockHookId XtAppAddBlockHook(XtAppContext app_context, XtBlockHookProc proc, XtPointer client_data);
void XtRemoveBlockHook(XtBlockHookId id);
Specifies the application context.
Specifies the block hook procedure.
Specifies the application-specific data to be passed to the block hook.
XtAppAddBlockHook registers the specified procedure and returns an identifier for it. The hook is called at any time in the future when the Intrinsics are about to block pending some input.
Block hook procedures are removed automatically and the XtBlockHookId is destroyed when the application context in which they were added is destroyed.
XtRemoveBlockHook removes the specified block hook procedure from the list in which it was registered.
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface
XtRemoveBlockHook(3) is an alias of XtAppAddBlockHook(3).