patch 7.4.1770
Problem:    Cannot use true color in the terminal.
Solution:   Add the 'guicolors' option. (Nikolai Pavlov)
diff --git a/src/term.h b/src/term.h
index 4e28486..4a7391c 100644
--- a/src/term.h
+++ b/src/term.h
@@ -87,10 +87,12 @@
     KS_CSV,	/* scroll region vertical */
 #endif
     KS_OP,	/* original color pair */
-    KS_U7	/* request cursor position */
+    KS_U7,	/* request cursor position */
+    KS_8F,	/* set foreground color (RGB) */
+    KS_8B	/* set background color (RGB) */
 };
 
-#define KS_LAST	    KS_U7
+#define KS_LAST	    KS_8B
 
 /*
  * the terminal capabilities are stored in this array
@@ -166,6 +168,8 @@
 #define T_RBG	(term_str(KS_RBG))	/* request background RGB */
 #define T_OP	(term_str(KS_OP))	/* original color pair */
 #define T_U7	(term_str(KS_U7))	/* request cursor position */
+#define T_8F	(term_str(KS_8F))	/* set foreground color (RGB) */
+#define T_8B	(term_str(KS_8B))	/* set background color (RGB) */
 
 #define TMODE_COOK  0	/* terminal mode for external cmds and Ex mode */
 #define TMODE_SLEEP 1	/* terminal mode for sleeping (cooked but no echo) */