The code assumes that "kmous" capability is for X10 mouse reporting,
so if an event for kmous happens it tries to decode it according to
the X10 protocol.

This breaks starting with ncurses 6.1 as the terminfo for xterm
started using the SGR sequence for xterm in 6.1.

This is a hacky, non-invasive patch which just assumes that the SGR
protocol is used.

diff -u -r ../mc-4.8.20/lib/tty/key.c ./lib/tty/key.c
--- ../mc-4.8.20/lib/tty/key.c	2017-03-04 18:51:38.000000000 +0100
+++ ./lib/tty/key.c	2018-02-08 23:19:38.207353992 +0100
@@ -2140,7 +2140,7 @@
                           || c == MCKEY_EXTENDED_MOUSE))
     {
         /* Mouse event */
-        xmouse_get_event (event, c == MCKEY_EXTENDED_MOUSE);
+        xmouse_get_event (event, 1);
         c = (event->type != 0) ? EV_MOUSE : EV_NONE;
     }
     else if (c == MCKEY_BRACKETED_PASTING_START)