Function tooltip_delay_timer_callback 

pub extern "C" fn tooltip_delay_timer_callback(
    _data: RefAny,
    info: TimerCallbackInfo,
) -> TimerCallbackReturn

Callback for the tooltip-delay timer.

Fires once after InputMetrics::hover_time_ms has elapsed while a node with a tooltip-bearing attribute was continuously hovered. The callback looks up the title / aria-label / alt attribute on the currently-hovered node, emits a ShowTooltip CallbackChange, and terminates — a single-shot timer. Movement to a different node (or any hover loss) removes and re-adds the timer from the platform layer, so the callback itself never needs to reschedule.