I keep getting the dialog "rdesktop is not responding" when running our rdesktop under gnome 3. I haven't completely pinpointed the conditions that trigger this, but it happens when doing Alt+Tab to switch back to the rdesktop window.
Bug 5337 implemented _NET_WM_PING support, which might be when this issue started.
This is with thinlinc-rdesktop-4.6.0post-5169.x86_64 and Fedora 23.
We'll start by diagnosing the issue.
I've seen this when running rdesktop in a ThinLinc session on SLES 12 as well.
The problem was also reported upstream issue , and a fix was commited .
I've used it a bit now, both directly on my workstation and in a ThinLinc session, and I cannot get this problem anymore. Should hopefully be solved now.