Function write_pointer_button_events_system

pub fn write_pointer_button_events_system(
    egui_global_settings: Res<'_, EguiGlobalSettings>,
    commands: Commands<'_, '_>,
    hovered_non_window_egui_context: Option<Res<'_, HoveredNonWindowEguiContext>>,
    modifier_keys_state: Res<'_, ModifierKeysState>,
    mouse_button_input_reader: EventReader<'_, '_, MouseButtonInput>,
    egui_input_event_writer: EventWriter<'_, EguiInputEvent>,
    egui_contexts: Query<'_, '_, (&EguiContextSettings, &EguiContextPointerPosition), With<EguiContext>>,
)

Reads MouseButtonInput events and wraps them into EguiInputEvent, can redirect events to HoveredNonWindowEguiContext, inserts, updates or removes the FocusedNonWindowEguiContext resource based on a hovered context.