Update cursor display using Xterm escape sequences

* lisp/term/xterm.el (xterm-update-cursor): New user option.
(xterm--init): Use it.
(xterm--post-command-hook): New function for all xterm
functionality installed in 'post-command-hook'.
(xterm--init-frame-title): Install it.
(xterm--init-update-cursor, xterm--set-cursor-type)
(xterm--update-cursor-type, xterm--update-cursor-color): New
functions.
(xterm--cursor-type-to-int): New constant.
* doc/emacs/display.texi (Cursor Display):
* etc/NEWS: Document the new feature.

1 files changed, 33 insertions, 20 deletions

diff --git a/doc/emacs/display.texi b/doc/emacs/display.texi
index 05a25323543..d475fc3cfde 100644
--- a/doc/emacs/display.texi
+++ b/doc/emacs/display.texi
@@ -2048,20 +2048,41 @@ variable @code{visible-cursor} is @code{nil} when Emacs starts or
 resumes, it uses the normal cursor.
 
 @vindex cursor-type
-  On a graphical display, many more properties of the text cursor can
-be altered.  To customize its color, change the @code{:background}
-attribute of the face named @code{cursor} (@pxref{Face
-Customization}).  (The other attributes of this face have no effect;
-the text shown under the cursor is drawn using the frame's background
-color.)  To change its shape, customize the buffer-local variable
-@code{cursor-type}; possible values are @code{box} (the default),
-@code{(box . @var{size})} (box cursor becoming a hollow box under
-masked images larger than @var{size} pixels in either dimension),
-@code{hollow} (a hollow box), @code{bar} (a vertical bar), @code{(bar
-. @var{n})} (a vertical bar @var{n} pixels wide), @code{hbar} (a
-horizontal bar), @code{(hbar . @var{n})} (a horizontal bar @var{n}
+  On a graphical display and many Xterm-compatible text terminals, the
+color and shape of the text cursor can be altered.  To customize its
+color, change the @code{:background} attribute of the face named
+@code{cursor} (@pxref{Face Customization}).  (The other attributes of
+this face have no effect; the text shown under the cursor is drawn using
+the frame's background color.)  To change its shape, customize the
+buffer-local variable @code{cursor-type}; possible values are @code{box}
+(the default), @code{(box . @var{size})} (box cursor becoming a hollow
+box under masked images larger than @var{size} pixels in either
+dimension), @code{hollow} (a hollow box), @code{bar} (a vertical bar),
+@code{(bar . @var{n})} (a vertical bar @var{n} pixels wide), @code{hbar}
+(a horizontal bar), @code{(hbar . @var{n})} (a horizontal bar @var{n}
 pixels tall), or @code{nil} (no cursor at all).
 
+@vindex xterm-update-cursor
+  On Xterm-compatible text terminals cursor customiztaion is controlled
+by the user option @code{xterm-update-cursor}.  Valid values are:
+@code{t} to update the cursor's color and shape, @code{type} to update
+the cursor's shape only, @code{color} to update the cursor's color only,
+and @code{nil} to not update the cursor's appearance.  Xterm-compatible
+text terminals can not display a hollow box and instead use a filled
+box.  Similarly, Xterm-compatible text terminals ignore the pixel sizes
+for @code{bar} and @code{hbar}.
+
+@findex hl-line-mode
+@findex global-hl-line-mode
+@cindex highlight current line
+  To make the cursor even more visible, you can use HL Line mode, a
+minor mode that highlights the line containing point.  Use @kbd{M-x
+hl-line-mode} to enable or disable it in the current buffer.  @kbd{M-x
+global-hl-line-mode} enables or disables the same mode globally.
+
+  The remaining controls only work on graphical displays where Emacs can
+fully control the way the cursor appears.
+
 @findex blink-cursor-mode
 @cindex cursor, blinking
 @cindex blinking cursor
@@ -2105,14 +2126,6 @@ non-blinking hollow box.  (For a bar cursor, it instead appears as a
 thinner bar.)  To turn off cursors in non-selected windows, change the
 variable @code{cursor-in-non-selected-windows} to @code{nil}.
 
-@findex hl-line-mode
-@findex global-hl-line-mode
-@cindex highlight current line
-  To make the cursor even more visible, you can use HL Line mode, a
-minor mode that highlights the line containing point.  Use @kbd{M-x
-hl-line-mode} to enable or disable it in the current buffer.  @kbd{M-x
-global-hl-line-mode} enables or disables the same mode globally.
-
 @node Line Truncation
 @section Line Truncation