Improve window dividers code.

* faces.el (window-divider): New default value.  Rewrite
doc-string.
(window-divider-first-pixel, window-divider-last-pixel): New
faces.
* dispextern.h (face_id): Add WINDOW_DIVIDER_FIRST_PIXEL_FACE_ID
and WINDOW_DIVIDER_LAST_PIXEL_FACE_ID.
* w32term.c (w32_draw_window_divider): Handle first and last
pixels specially.
* w32term.h (w32_fill_area_abs): New function.
* xdisp.c (x_draw_right_divider): Don't draw over bottom
divider.
* xfaces.c (realize_basic_faces): Handle new face ids.
* xfns.c (Fx_create_frame): Call x_default_parameter for right
and bottom divider width.
* xterm.c (x_draw_window_divider): Handle first and last pixels
specially.

1 files changed, 12 insertions, 0 deletions

diff --git a/etc/NEWS b/etc/NEWS
index cfcb74cf782..11cb240890a 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -197,6 +197,18 @@ command `frame-configuration-to-register' still exists, but is unbound.
 These are normal hooks run when an Emacs frame gains or loses input focus.
 
 ---
+*** Emacs can now draw dividers between adjacent windows.  To put
+dividers between side-by-side windows customize the frame parameter
+right-divider-width to some positive integer.  To put dividers between
+vertically stacked windows set the frame parameter bottom-divider-width
+to some positive integer.  Dividers can be dragged with the mouse and
+show a corresponding cursor when the mouse hovers over them.  The
+appearance of dividers can be changed by customizing the basic faces
+window-divider, window-divider-first-pixel and window-divider-last-pixel
+where the latter two are useful to provide a 3D effect or to better set
+dividers apart from surrounding display objects.
+
+---
 *** `split-window' is now a non-interactive function, not a command.
 As a command, it was a special case of `C-x 2' (`split-window-below'),
 and as such superfluous.  After being reimplemented in Lisp, its