@kindex line-height @r{(text property)}
A newline can have a @code{line-height} text or overlay property
that controls the total height of the display line ending in that
-newline. If the property value is zero, the displayed height of the
+newline.
+
+ If the property value is a list @code{(@var{height} @var{total})},
+then @var{height} is used as the actual property value for the
+@code{line-height}, and @var{total} specifies the total displayed
+height of the line, so the line spacing added below the line equals
+the @var{total} height minus the actual line height. In this case,
+the other ways to specify the line spacing are ignored.
+
+ If the property value is @code{t}, the displayed height of the
line is exactly what its contents demand; no line-spacing is added.
This case is useful for tiling small images or image slices without
adding blank areas between the images.
- If the property value is not zero, it is a height spec. A height
+ If the property value is not @code{t}, it is a height spec. A height
spec stands for a numeric height value; this heigh spec specifies the
actual line height, @var{line-height}. There are several ways to
write a height spec; here's how each of them translates into a numeric
@item @var{float}
If the height spec is a float, @var{float}, the numeric height value
is @var{float} times the frame's default line height.
-@item (@var{ratio} . @var{face})
+@item (@var{face} . @var{ratio})
If the height spec is a cons of the format shown, the numeric height
is @var{ratio} times the height of face @var{face}. @var{ratio} can
-be any type of number. If @var{face} is @code{t}, it refers to the
-current face.
+be any type of number, or @code{nil} which means a ratio of 1.
+If @var{face} is @code{t}, it refers to the current face.
+@item (@code{nil} . @var{ratio})
+If the height spec is a cons of the format shown, the numeric height
+is @var{ratio} times the height of the contents of the line.
@end table
- Thus, any valid nonzero property value specifies a height in pixels,
+ Thus, any valid non-@code{t} property value specifies a height in pixels,
@var{line-height}, one way or another. If the line contents' height
is less than @var{line-height}, Emacs adds extra vertical space above
the line to achieve the total height @var{line-height}. Otherwise,
numeric height value specifies the line spacing, rather than the line
height.
- There is one exception, however: if the @var{line-spacing} value is
-a cons @code{(total . @var{spacing})}, then @var{spacing} itself is
-treated as a heigh spec, and specifies the total displayed height of
-the line, so the line spacing equals the specified amount minus the
-line height. This differs from using the @code{line-height} property
-because it adds space at the bottom of the line instead of the top.
-
- If you specify both @code{line-spacing} using @code{total} and
-@code{line-height}, they are not redundant. First @code{line-height}
-goes to work, adding space above the line contents. Then
-@code{line-spacing} goes to work, adding space below the contents.
-
@node Faces
@section Faces
@cindex faces
* Defining Faces:: How to define a face with @code{defface}.
* Face Attributes:: What is in a face?
* Attribute Functions:: Functions to examine and set face attributes.
-* Merging Faces:: How Emacs combines the faces specified for a character.
+* Displaying Faces:: How Emacs combines the faces specified for a character.
* Font Selection:: Finding the best available font for a face.
* Face Functions:: How to define and examine faces.
* Auto Faces:: Hook for automatic face assignment.
attributes}. This table lists all the face attributes, and what they
mean. Note that in general, more than one face can be specified for a
given piece of text; when that happens, the attributes of all the faces
-are merged to specify how to display the text. @xref{Merging Faces}.
+are merged to specify how to display the text. @xref{Displaying Faces}.
In Emacs 21, any attribute in a face can have the value
@code{unspecified}. This means the face doesn't specify that attribute.
the terminal supports the feature.
@item :foreground
-Foreground color, a string.
+Foreground color, a string. The value can be a system-defined color
+name, or a hexadecimal color specification of the form
+@samp{#@var{rr}@var{gg}@var{bb}}. (@samp{#000000} is black,
+@samp{#ff0000} is red, @samp{#00ff00} is green, @samp{#0000ff} is
+blue, and @samp{#ffffff} is white.)
@item :background
-Background color, a string.
+Background color, a string, like the foreground color.
@item :inverse-video
Whether or not characters should be displayed in inverse video. The
This function returns the @code{:inverse-video} attribute of face @var{face}.
@end defun
-@node Merging Faces
-@subsection Merging Faces for Display
+@node Displaying Faces
+@subsection Displaying Faces
Here are the ways to specify which faces to use for display of text:
@kindex keymap @r{(button property)}
The button's keymap, defining bindings active within the button
region. By default this is the usual button region keymap, stored
-in the variable @code{button-map}, which defines @key{RET} and
-@key{mouse-2} to invoke the button.
+in the variable @code{button-map}, which defines @key{RET},
+@key{mouse-1} (if @var{mouse-1-click-follows-link} is set),
+and @key{mouse-2} to invoke the button.
@item type
@kindex type @r{(button property)}
A string displayed by the Emacs tool-tip help system; by default,
@code{"mouse-2, RET: Push this button"}.
+@item follow-link
+@kindex follow-link @r{(button property)}
+The follow-link property, defining how a @key{mouse-1} click behaves
+on this button, @xref{Enabling Mouse-1 to Follow Links}.
@item button
@kindex button @r{(button property)}
All buttons have a non-@code{nil} @code{button} property, which may be useful
buttons in an Emacs buffer.
@code{push-button} is the command that a user uses to actually `push'
-a button, and is bound by default in the button itself to @key{RET}
+a button, and is bound by default in the button itself to @key{RET},
+to @key{mouse-1} (if @var{mouse-1-click-follows-link} is set),
and to @key{mouse-2} using a region-specific keymap. Commands
that are useful outside the buttons itself, such as
@code{forward-button} and @code{backward-button} are additionally