firstValid
Returns the first #GHook in a #GHookList which has not been destroyed. The reference count for the #GHook is incremented, so you must call g_hook_unref() to restore it when no longer needed. (Or call g_hook_next_valid() if you are stepping through the #GHookList.)
Return
the first valid #GHook, or null if none are valid
Parameters
hookList
a #GHookList
mayBeInCall
true if hooks which are currently running (e.g. in another thread) are considered valid. If set to false, these are skipped