[Bug-XBoard] Again XBoard copy

[h.g. muller]

The copying of positions and games now works fine in XBoard.
But another problem surfaced: people also want to copy text from
the engine-output window. I guess this is a very legitimate wish:
people want to analyze positions, to see at which depth the engine
finds the solution to a tactical problem, and then post that Thinking
Output on a forum.

Knowing about the selection vs clipboard probem, I tried to select
text in the Engine-Output window (which is a read-only text widget),
and indeed I am able to copy that to another window (I tried the
XBoard Edit-Comment popup, but I suppose other writable text
widgets of X applications would work as well), by pressing Shift+Insert.
(I also tried right-clicking, but that did not work.)

But gedit ignores the selection, and can only paste from clipboard.
How can I transfer the selection to the clipboard in X? Is there a key stroke
or a mouse click for that? Or must we define our own routine to make
that transfer, and provide a button or context menu or define a mouse click
to invoke that routine?