sendToMainloopAsync
Used from an I/O job to send a callback to be run asynchronously in the thread that the job was started from. The callback will be run when the main loop is available, but at that time the I/O job might have finished. The return value from the callback is ignored.
Note that if you are passing the @user_data from g_io_scheduler_push_job() on to this function you have to ensure that it is not freed before
Parameters
func
a #GSourceFunc callback that will be called in the original thread