Page up ad page down.

[gavron]

I have a rather silly problem that is presumably not documented or at 
least not in these terms:  when I use the Page Up/Page Down keys to 
browse a LyX manual the paging appears not to follow the screen size.. 
even appears to be somewhat random - ie. a little more or a little less 
than a page  - eg. when I use repeated pageups/pagedowns to toggle 
viewing of two successive pages.   There might a be a good reason for 
this and it might have its use when writing a document rather than 
browsing a manual - though I don't see the philosopy behind it at this 
point..  Doesn't sound like a big deal but at times it has me totally 
confused as to what page I am on..  whether I pressed page up twice 
instead of once and have landed on a different page altogether.. etc.. 
I have fiddled so many settings over the last few days that I'm 
beginning to think that this might be an indirect consequence of some 
changes that I have made.. since I don't remember noticing this when I 
started using LyX..  has anyone noticed this behavior and could possibly 
suggest a (keyboard-driven) solution?  I would be content with a 
pageup/page down solution that really moves one physical  screen at a 
time regardless of the document's structure .. or possibly suggest some 
means of binding keys to a command that moves one half-screen up or 
down. Thanks. Chris.