patch 7.4.1974
Problem:    GUI has a problem with some termcodes.
Solution:   Handle negative numbers. (Kazunobu Kuriyama)
diff --git a/src/gui.c b/src/gui.c
index 6e8a904..59acc13 100644
--- a/src/gui.c
+++ b/src/gui.c
@@ -1773,7 +1773,7 @@
 	if (s[0] == ESC && s[1] == '|')
 	{
 	    p = s + 2;
-	    if (VIM_ISDIGIT(*p))
+	    if (VIM_ISDIGIT(*p) || (*p == '-' && VIM_ISDIGIT(*(p + 1))))
 	    {
 		arg1 = getdigits(&p);
 		if (p > s + len)