It's useful to have a working X server if a client holds a grab when it triggers a debugger breakpoint

David Campbell david at
Mon May 25 18:56:58 PDT 2009

Owen Taylor wrote:
> On Tue, 2009-05-26 at 10:00 +1000, David Campbell wrote:
>> Hi,
>> Many/most GUI toolkits implement pop up menus using grabs.  This can 
>> cause major desktop lockups when debugging GUI applications, because 
>> hitting breakpoints in pop up menu callback code will occur while a grab 
>> is active.
>> Reaching a breakpoint while a grab is active indefinitely locks up the X 
>> server, leaving a standalone desktop user the only option but to power 
>> down and suffer potential data loss.
> Or kill the debugging process by switching to a VT or remotely
Hi Owen,

Thanks for your reply.

By "switching to a VT", did you mean pressing CTRL-ALT-<number> to 
switch to a virtual terminal?

That doesn't work for me, due to the grab.  Pressing those keystrokes is 
unresponsive, thus for a standalone system in a location where there are 
no other computers, it still appears that the only option in the 
situation of hitting a breakpoint during a grab, is to force a power 
down and reboot.

Do you know of any other options?

-- Dave

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