An interface or its children can be altered programmatically in many ways. This chapter describes APIs for the most common of these.
Note:
By default, each CAPI interface runs in its process. It is important to understand that an on-screen interface and its elements must be accessed only in the process of that interface. In most circumstances the user alters the interface by a callback inside the interface, which will automatically happen in the correct process. However, calls from other processes (including other CAPI interfaces) should use execute-with-interface, execute-with-interface-if-alive, apply-in-pane-process or apply-in-pane-process-if-alive.
CAPI User Guide and Reference Manual (Unix version) - 25 Feb 2015