bool g_querying_action;

void mytimer()
{
	WDL_ASSERT(g_querying_action == true);
	const int res = PromptForAction(0,0,0);	
	if (res == 0) return;
	plugin_register("-timer",(void *)&mytimer);
	g_querying_action = false;
	if (res > 0)
	{
		// user selected the action res!
	}
	else
	{
		// user (e.g.) closed window without selecting an action
	}
}

// when you want to prompt a user:
PromptForAction(1,0,0);
if (!g_querying_action)
{
	g_querying_action = true;
	plugin_register("timer", (void *)&mytimer);
}