Returns a list of targets that are present on the clipboard, or null if there aren’t any targets available.
The returned list must be freed with g_free. This function waits for the data to be received using the main loop, so events, timeouts, etc, may be dispatched during the wait.
location to store an array of targets. The result stored here must be freed with g_free.
location to store number of items in
true if any targets are present on the clipboard, otherwise false.