Intermittent problems with cut/copy and paste (using CUA keys) between Emacs and other programs

[nljlistbox2@gmail.com]

I'm having occasional problems with the clipboard / kill ring (?) and I am wondering how to go about narrowing the problem down sufficiently to report a bug.

I have GNU Emacs 24.3.1 (x86_64-redhat-linux-gnu, GTK+ Version 3.8.2) (of 2013-08-14 on buildvm-15.phx2.fedoraproject.org) on Fedora 19 GNU/Linux 3.11.8-200.fc19.x86_64 (of Wed Nov 13 16:29:59 UTC 2013) and I have been suffering the misfortune of using Gnome 3. I use CUA keys for cut/copy/paste.

The problem is that occasionally when I try to paste text in to Emacs that I cut/copied from an another program (usually Firefox), either nothing happens or the text that gets pasted is something I cut/copied in Emacs at some point previously. Likewise, occasionally when I cut/copy in Emacs and paste in to another program, my text from Emacs doesn't get pasted. Most of the time, however, these operations work as expected.

That is, it seems as if the clipboard / kill ring inside Emacs sometimes gets dissociated from the system clipboard.

The problem occurs maybe once or twice a week and only (I believe) after I've had Emacs running for a few days, not when it was freshly started, but I am not 100% certain that this statement is true. The problem has been ongoing for several months -- certainly since September, and I suspect it's been happening since I set up this computer in July.

After the problem occurs, sometimes (always?) if I repeat the operation using the Edit menu, the operation works, and thereafter the CUA keys start working again (for a while at least). 

One difficulty with observing what's going on and narrowing it down is that Ctrl-c, Alt-Tab, Ctrl-v is so much second nature that it happens below the level of consciousness, so when it fails I'm jarred out of my thought space and have no recollection of what specifically I just did. However, once the problem happens once, if I repeat the operation it almost always fails again, so at least I can confirm it really happened even if I can't identify anything I specifically did to make it happen in the first place.

Thanks in advance for any pointers anyone can provide.

N. Jackson.