Query background for gnome terminal version 3.22 (Bug#29716)

* lisp/term/xterm.el (xterm--version-handler): Use
xterm--report-background-handler for terminals reporting minor version
4000 and above.

lisp/term/xterm.el

@@ -670,8 +670,13 @@ Return the pasted text as a string."
         (when (and (> version 2000) (equal (match-string 1 str) "1"))
           ;; Hack attack!  bug#16988: gnome-terminal reports "1;NNNN;0"
           ;; with a large NNNN but is based on a rather old xterm code.
-          ;; Gnome terminal 3.6.1 reports 1;3406;0
           ;; Gnome terminal 2.32.1 reports 1;2802;0
+          ;; Gnome terminal 3.6.1 reports 1;3406;0
+          ;; Gnome terminal 3.22.2 reports 1;4601;0 and *does* support
+          ;; background color querying (Bug#29716).
+          (when (> version 4000)
+            (xterm--query "\e]11;?\e\\"
+                          '(("\e]11;" .  xterm--report-background-handler))))
           (setq version 200))
         (when (equal (match-string 1 str) "83")
           ;; `screen' (which returns 83;40003;0) seems to also lack support for