Fix for libgtk-xmhtml scroll bug

[deman win tue nl (Ronald de Man)]

Finally I've got gnome-help-browser to work again. I noticed that
the scrolling down bug is still present. It's very noticeable in for
example info:libc. I've looked through gnome-libs/gtk-xmhtml and found
the following fix.

--- XmHTML.c	Sat Nov 28 10:53:34 1998
+++ XmHTML.c	Sat Nov 28 10:55:03 1998
@@ -2857,7 +2857,7 @@
			html->html.scroll_y = value;
 
			/* save new paint engine start */
-			html->html.paint_start = html->html.paint_end;
+			html->html.paint_end = html->html.paint_start;
 
			/* small increment */
			if(inc < html->html.work_height)

Hopefully somebody will check if this is the right way to fix it.

Ronald