How to debug a buggy running GUI application?

Question

Suppose the GUI applications are not given names in its GUI, so you don't know what to check in 'ps -A', i.e. the nameless applications in the task bar. How do I know which GUI application belong to what process and start debugging its errors (i.e. GUI frozen, program crash...)? With CLI applications, I can use attach the process to GDB and start investigating it.

Answer 1

To search for a specific PID i would invoke pstree -p which visualize the relation of processes. With this it's mostly possible to narrow down all eligible processes.

This approach assumes that the window in question is at least a child of a process that you are aware of.