Added a method PANE-BORDER that works just like PANE-VIEWPORT and PANE-SCROLLER, only for BORDER-PANEs. It is not in the spec, but so is the BORDER-PANE as a whole. (And, yes, I needed it.)
Added a method PANE-BORDER that works just like PANE-VIEWPORT and
PANE-SCROLLER, only for BORDER-PANEs. It is not in the spec, but so
is the BORDER-PANE as a whole. (And, yes, I needed it.)

In addition to this it changes the IFs in PANE-VIEWPORT and
PANE-SCROLLER to WHENs (both had no else-forms).

(Minor change:
 Five changes in the comments: The section titles of the different
 panes are made consistent. (Most of them were of the pattern
 "FOO PANE", only five of them "FOO-PANE"; as I liked the former
 pattern more, they are now all of that pattern.))

slyrus/mcclim,onixie/mcclim,antifuchs/mcclim,swflint/McCLIM,onixie/mcclim,antifuchs/mcclim,onixie/mcclim,swflint/McCLIM,slyrus/mcclim,swflint/McCLIM