Show available jobs and job chains in <on_return_code> dialogue

Description
The dialog for return codes that is available with a job chain node has a field for the state in the next_state box. And there is an input field for the job chain in the add_order box. The values for these input fields must be typed in.
Desired behaviour
The input field state should be a combo box that contains the actual states of the actual job chain
The input field job_chain should be a combo box that contains all job chains in the actual folder. Also there should be a browse button to select job chains that are in other folders.