In many cases you don't want to use a bunch of MessageBox() calls in a
VB6 client you are developing against LibreOffice, as that disrupts
the working of the client. The developer might not mind, but other
people trying it will be bothered by having to click through a stream
of message boxes. Also, it is hard to correctly interpret the
chronological sequence of LibreOffice's own debug output lines and
such MessageBox() windows.

WScript.Echo calls from a VBScript client are a bit better as they
don't require any click-through, but still there is the problem of
correlating with LibreOffice's own debug output.

Setting this StatusBar property causes LibreOffice to output a
SAL_INFO line with the tag "extensions.olebridge". Thus they are
automatically merged with LibreOffice's own output and displayed in
correct order.

Sure, the intent of some existing 3rd-party client that sets this
property would be to actually display a message in the status bar
(whatever that corresponds to in LibreOffice), but until some such
need is actually encountered, it's enough to just use it for this
debug output functionality. After all, this property was not
implemented at all earlier, so adding it now with somewhat special
semantics is not a regression.

(Note that on the Calc side, ooo.vba.excel.XApplication did have a
StatusBar property already, and setting that does seem to attempt to
display the text in some way. Possibly it should be enhanced to also
do the SAL_INFO thing, for consistency? And possibly we should also
have the message being displayed in the same fashion on the Writer
side?)

Change-Id: I5bf1e776d6401adfc43a558a2d919bd675298e1a
Reviewed-on: https://gerrit.libreoffice.org/55413Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Tor Lillqvist <tml@collabora.com>