KDE (or X?) clipboard goes stupid

[Stephen Dowdy]

On 12/09/2017 12:47 PM, Jerome Yuzyk wrote:
> [kf5 5.38, plasma-workspace-5.10.5, Fedora 25]
> 
> My KDE/X clipboard goes astray sometimes. I Copy URL to clipboard from KMail, 
> for example, and when I paste I get something from a day ago pasted.
> 
> Is there any way to reset that clipboard without restarting X or KDE? I'm not 
> talking about Klipper, but the default clipboard.
> 
> 

There's a lot of "cut/paste" mechanisms in play.

X11 has a Primary and Secondary buffer, but there's also a Clipboard.
selecting text via mouse in something like xterm puts that text into the Primary buffer.
Using CTRL-C/V uses the Clipboard.  (this is all generalizations).

You can use a tool like 'xsel' or 'xclip' to manipulate all three of those buffers:
To see what's in each buffer:

    for buf in primary secondary clipboard; do printf "\n[${buf}]\n"; xsel -o --${buf} ; done; printf "\n"

'xclipboard' monitors and caches clipboard content as applications store stuff there, so you can recall previous versions.
(it's got some scrolling display issues, so you might have to move the cursor around to see things well)

Conceptually, i like klipper, because it allows actions to be defined.

This allows me to almost emulate what CDE (Common Desktop Environment) used to have which was the Deskset Tools text-menu stuff (a file you could configure to hold a hierarchy of named transformation actions).  I used that to {in,out}dent selections 4 chars, Uppercase/LowerCase selections,  Reflow text in a buffer, etc.

However, in practice, Klipper, especially in KDE Plasma 5 has been "problematical" for me.  I tend to use the standalone klipper application and turn off the plasma builtin one.

But, yesterday, i ran into *thunderbird* no longer being able to operate on the selection or clipboard buffers (i thought it was klipper acting up).

Restarting thunderbird fixed that problem.

Klipper has an option to "synchronize" the clipboard with the primary selection.  sometimes this also causes grief.  You may want to check that if you have klipper enabled.  (it may be messing with you)

--stephen