Re: tooltip can be displayed outside the screen

[Juri Linkov <juri@jurta.org>]

>> >    Sorry I need to give a little more explanation.  In the two images
>> >    Emacs frame is placed on the bottom edge of the screen.  When I
>> >    move the mouse pointer to the mode line, Emacs 22.0.50 tries to
>> >    place the tooltip below the mouse pointer.  But enough pixels are
>> >    not left between the point just below the mouse pointer and the
>> >    bottom edge of the screen. As a consequence the tooltip appears
>> >    partly off the edge of the screen.
>> >
>> >Can someone please fix this and ack?
>> 
>> Fixed.
>
> Jan fixed this for X only; I now fixed it for w32.  I think someone
> with access to the Mac needs to fix it in macfns.c.

I noticed that the user option `tooltip-y-offset' doesn't do what it is
intended to do.  Instead of specifying the Y offset, it actually specifies
Y offset + height of the tooltip frame.  With a different font size
the tooltip might overlap the mouse pointer (with a bigger font) or might
be placed too far from the mouse pointer (with a smaller font).  This looks
like a bug.

OTOH, `tooltip-x-offset' properly specifies the X offset.  I suggest
to duplicate the implementation of calculating the X absolute coordinate
of the tooltip frame position, for calculating the Y absolute coordinate
with replacing `x' with `y' and `width' with `height' in the copy of the
code.  This will make the logic of these two options exactly the same.

This change will also require fixing the default value of `tooltip-y-offset'
from 40 (which currently is the sum of the real Y offset + the size of
the default font) to e.g. 18.

-- 
Juri Linkov
http://www.jurta.org/emacs/