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 will prompt the user to select one of the candidates.