Windows 7 is managing status icon visibility across process lifetime,
which did not work with GTK+ create icons. Apparently the mechanism
does not require use of new API (like suggested by MSDN), but it is
enough to give a "unique" tooltip at creation time.
Formerly this initial tooltip was not set at all, later setting via
gtk_status_icon_set_tooltip_text() is not enough, but luckily
different follow-up tooltips don't disturb the intended behavior.
(cherry picked from commit ae0544c6)
(cherry picked from commit 8a9d458b)