Debugging is sometimes very hard for distributed computations.
We provide two methods to help debugging on X window system:
1. the diagnostic messages from the engine are displayed in a xterm
2. the engine can pop up a window to input debug commands.
For example ox_asir, which is
the OpenXM server of Risa/Asir, can pop up a window to input
debug commands and the debugging similar to that on usual terminals is possible.
One can also send SIGINT by using SM_control_to_debug_mode
and it provides a similar functionality to entering the debugging
mode from a keyboard interruption.