xif_main_loop(+ExitCond, +Context)
     xif_main_loop(+Displayable, +ExitCond, +Context)

These handle both ProXT and ProXL events. ProXT and ProXL have their own event handling mechanisms. If you combine ProXL and ProXT callbacks, you must use one of xif_main_loop/[0,1,2,3] instead of xtMainLoop/0.

These predicates are direct analogues of the ProXL predicates handle_events/[0,1,2,3], and are used in exactly the same way. See the ProXL documentation for more detailed information on the arguments, and how they tie in with ProXL callbacks.

If you do not use ProXL callbacks, you do not need these predicates; you can just call xtMainLoop/0. You may mix ProXT and ProXL callbacks freely.