bug#23806: 24.5; can not set line height

[ynyaaa@gmail.com]

Eli Zaretskii <eliz@gnu.org> writes:

> The node "Line Height" in the ELisp manual describes the line-spacing
> variable and frame parameter, which are more general-purpose ways of
> controlling vertical layout of text.

The manual also describes the line-spacing property at the newlines,
which has same problems as the line-height property.

I want to use the line-height property because the line-spacing variable
can not affect partial buffer contents and can not add spacing both
above and below lines.


By the way it is written in the manual,
       If the property value is a list of the form ‘(HEIGHT TOTAL)’,
    (snip) In
    this case, the other ways to specify the line spacing are ignored.

Setting the line-height property to '(1.0 1.0) ignores the line-spacing
property, but the line-spacing variable or frame parameter takes effect.

Setting the line-height property to 't ignores the line-spacing
property, this behavior is not documented.


In the manual:
       Finally, a newline can have a ‘line-spacing’ text or overlay property
    that overrides the default frame line spacing and the buffer local
    ‘line-spacing’ variable, for the display line ending in that newline.

The line-spacing property overrides the line-spacing variable or frame
parameter only if the property value is bigger.