GObject.signal_handler_find

function signal_handler_find(instance: GObject.Object, mask: GObject.SignalMatchType, signal_id: Number(guint), detail: GLib.Quark, closure: Function, func: void, data: void): Number(gulong) {
    // Gjs wrapper for g_signal_handler_find()
}

Finds the first signal handler that matches certain selection criteria. The criteria mask is passed as an OR-ed combination of GObject.SignalMatchType flags, and the criteria values are passed as arguments. The match mask has to be non-0 for successful matches. If no handler was found, 0 is returned.

instance: The instance owning the signal handler to be found.
mask: Mask indicating which of signal_id, detail, closure, func and/or data the handler has to match.
signal_id: Signal the handler has to be connected to.
detail: Signal detail the handler has to be connected to.
closure: The closure the handler will invoke.
func: The C closure callback of the handler (useless for non-C closures).
data: The closure data of the handler's closure.
Returns: A valid non-0 signal handler id for a successful match.