urxvt breaks backwards scroll in "less -X"

[Stefan Möhl]

Not sure if this is the right group to post this in, if not, please
give me a pointer!

I have recently switched to rxvt-unicode (a.k.a. urxvt) under Cygwin,
but I have come on to a problem. When I use 'less', I always have the
switch "-X" enabled, so that less doesn't clear the screen when I quit
less. This allows me to keep seeing what was in the file when I am
about to enter a command.

Unfortunately, on urxvt, this results in the screen clearing whenever
I do a backwards movement (back a page or a line) in less - and
consequently 'man' too, leaving me with a single line of text in the
top row until I do a forward movement.

The only reference I could find to a similar problem was this forum
post regarding Enlightenment:

http://forums.gentoo.org/viewtopic-t-937654-start-0.html

In that case, the problem was a development release of Enlightenment,
and that has made me concerned that the problem is really the X-window
manager, not less or urxvt.

I am running

cygwin 1.7.17-1
X.org server 1.13.0-1
rxvt-unicode 9.15-1 in client/server mode
less 444-1

under Windows XP SP3.

Does anyone have any idea?