(Window Frame Parameters): New @defvar for `line-spacing'.

diff --git a/lispref/frames.texi b/lispref/frames.texi
index 655232a8869ecb522da133983b0f7fe9569e7db0..e3e92c621e9e2bdda8b8277086656b121fca0b0b 100644 (file)
--- a/lispref/frames.texi
+++ b/lispref/frames.texi
@@ -605,6 +605,25 @@ it and see if it works.)
 @end ignore
 @end table
 
+@defvar line-spacing
+When this permanently buffer-local variable is non-nil, if its value is
+an integer, that many pixels of extra space are put below each line.  If
+the value is a floating point number, compute the spacing by multiplying
+the value by the default frame line height.
+
+Note that this variable and the frame parameter @code{line-spacing}
+(described above) control different things.  The frame parameter is
+involved in setting the frame line height (@pxref{Creating Frames}),
+while the buffer-local variable is for already-created frames.
+
+For example, if the frame parameter is nil, a variable value of 1.0
+``double-spaces'' the display because for every line of text, there is
+an additional full line of space put below it.  Likewise, a value of 2.0
+``triple-spaces'' the display, and so forth.  If, on the other hand, the
+frame parameter is 10, a variable value of 10 would effectively put 20
+pixels of space under the text.
+@end defvar
+
 @defvar blink-cursor-alist
 This variable specifies how to blink the cursor.  Each element has the
 form @code{(@var{on-state} . @var{off-state})}.  Whenever the cursor