I've been struggling with a strange/erratic behaviour when inputing data in a program (in this case, it was grisbi but it could be with other programs as well) to finally discover it was klipper's interaction that causes some buggy interaction with the clipboard

in grisbi, one as to enter values in successive input fields and the symptom I had was that every time I had drop-down lists with a pre-selected value, this value that normally stays selected/highlighted just got unselected after a very short time (usually tenths of a seconds)
that particular behaviour was very disturbing to effectively use that particular software

and after digging a bit, I discovered that 2 instances of klipper was launched (and both appeared in the system tray with few differences between the two)

one was launched through the plasmashell program (I found it with lsof that relate the pid to the klipper.mo file)
and the other one was launch with the klipper binary (/usr/bin/klipper)

and both instances show different menus: for instance, only the latter (the real klipper process) can be stopped with the "Quit" through the menu

so, once I managed to stop the klipper program, everything was back to normal

it seems to me that the clipboard interaction is so buggy when those 2 klipper are launch, that it would be important to avoid such situation, maybe by forbidding /usr/bin/klipper altogether, or at least to test when launch that another instance is not already interacting with the clipboard

Reproducible: Always

Steps to Reproduce:
1. check that klipper is already launched through plasmashell (lsof | grep klipper)
2. launch /usr/bin/klipper (it should not be running)
3. use a software that interacts heavily with clipboard and proposes a pre-selected drop-down list (in my example, grisbi is a very good candidate, but I could not find another one)

Actual Results:  
pre-selected fields just got unselected very quickly, making it hard to type another value, thus, by typing something else it gets appends at the end of the existing 

Expected Results:  
the normal behaviour would be that it stays selected, hence allowing easy replacement of the value