Support `select-active-regions' with xterm

This allows Emacs to save the active region to the user's
primary selection on supported terminals.  The behavior follows
the existing `select-active-regions' variable and requires
`xterm-select-active-regions' to be non-nil.

* src/keyboard.c (command_loop_1):
* lisp/frame.el (display-selections-p): On text terminals, check
terminal parameter `xterm--set-selections' and variable
`xterm-select-active-regions' when deciding whether to update
primary selection. (bug#55883)
* lisp/term/xterm.el (xterm-select-active-regions): New
defcustom.

1 files changed, 9 insertions, 1 deletions

diff --git a/src/keyboard.c b/src/keyboard.c
index 60ff8f5ea6a..cd92cf8d4ac 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -1567,9 +1567,15 @@ command_loop_1 (void)
             call0 (Qdeactivate_mark);
           else
             {
+              Lisp_Object symval;
               /* Even if not deactivating the mark, set PRIMARY if
                  `select-active-regions' is non-nil.  */
-              if (!NILP (Fwindow_system (Qnil))
+              if ((!NILP (Fwindow_system (Qnil))
+                   || ((symval =
+                        find_symbol_value (Qxterm_select_active_regions),
+                        (!EQ (symval, Qunbound) && !NILP (symval)))
+                       && !NILP (Fterminal_parameter (Qnil,
+                                                      Qxterm__set_selection))))
                   /* Even if mark_active is non-nil, the actual buffer
                      marker may not have been set yet (Bug#7044).  */
                   && XMARKER (BVAR (current_buffer, mark))->buffer
@@ -12163,6 +12169,8 @@ syms_of_keyboard (void)
   DEFSYM (Qpolling_period, "polling-period");
 
   DEFSYM (Qgui_set_selection, "gui-set-selection");
+  DEFSYM (Qxterm__set_selection, "xterm--set-selection");
+  DEFSYM (Qxterm_select_active_regions, "xterm-select-active-regions");
 
   /* The primary selection.  */
   DEFSYM (QPRIMARY, "PRIMARY");