bug#19060: [FIX INCLUDED] Off-by-one-line scrolling bug in window_scroll_pixel_based

[martin rudalics <rudalics@gmx.at>]

 >> (you can use the function `window--dump-frame' for that) and what the
 >> height stored by `desktop-save' is.  I suppose this is somewhere in a
 >> cons whose car is something like `height' or `frame-height' or the like.
 >
 > I am afraid, I wasn't able to use that function.. How to evaluate it? I tried a few command but they didn't work.

M-: (window--dump-frame)

The results appear in a buffer called *window-frame-dump*.  Do this
please once before exiting one session and once after entering the
subsequent session and post the respective buffer contents here.  And
please do that in the appropriate thread, namely for bug#19048.

 > First I removed the current desktop and history files. So I started
 > Emacs and moved it so that it was centered in the Windows desktop (I
 > tried this with the Cygwin build..). Then I closed Emacs and it asked
 > to save the desktop. Yes - and this generated the "desktop-00"
 > file. Then I restarted Emacs and closed it obtaining the "desktop-01"
 > file. I repeated this 2 times obtaining "desktop-03". After repeating
 > this a few times I obtained the "desktop" file: now Emacs frame is
 > conspicuously short.

I suppose the frame height is stored in the (height . xx) conses.  In
desktop-00 you have (height . 34), in desktop-01 (height . 33) and in
desktop-03 (height . 31).  So your frame height seems to decrease by one
line every time you restore it.  Using `window--dump-frame' we should be
able to see what the frame height was before exiting one session and
after restoring it in another one and hopefully why the frame decreases
by that line.

Thanks, martin