What I did: dolphin, mark file, right click, activity, click on . what happens: everything stocks, black screen with moucse cursor, Windows and plasmashell comes up again with all Windows and trays still open except dolphin. gdb output:
GNU gdb (Ubuntu 7.10-1ubuntu2) 7.10
Copyright (C) 2015 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from /usr/bin/plasmashell...(no debugging symbols found)...done.
Attaching to program: /usr/bin/plasmashell, process 4052
Could not attach to process. If your uid matches the uid of the target
process, check the setting of /proc/sys/kernel/yama/ptrace_scope, or try
again as the root user. For more details, see /etc/sysctl.d/10-ptrace.conf
ptrace: Vorgang nicht zulässig.
(gdb)
Thank you for asking for needed further details. Kubuntu 15.10, Nvidia Zotac Geforce GT750, NVidia 352 installed.
I experienced exactly the same bug. I didn't manage find a solution (even if still searching for it)..I can only suggest to use keyboard shortcuts in Dolphin whenever it's possible because it's a mouse-click related bug