Calls the completion-function in a text-input-pane.
The function
text-input-pane-complete-text
calls the
completion-function
of
pane
with the current
text
. If this call is successful, then the
text
of
pane
is set to the result, and
text-input-pane-complete-text
returns this result. Otherwise,
result
is
nil
.
Note: the
completion-function
may return a list of completion candidates, in which case
text-input-pane-complete-text
prompts the user to select one of the candidates.