patch 7.4.2263
Problem:    :filter does not work for many commands.  Can only get matching
            messages.
Solution:   Make :filter work for :command, :map, :list, :number and :print.
            Make ":filter!" show non-matching lines.
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 94216b3..44f6c1e 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -1925,6 +1925,13 @@
 			    if (!checkforcmd(&p, "filter", 4)
 						|| *p == NUL || ends_excmd(*p))
 				break;
+			    if (*p == '!')
+			    {
+				cmdmod.filter_force = TRUE;
+				p = skipwhite(p + 1);
+				if (*p == NUL || ends_excmd(*p))
+				    break;
+			    }
 			    p = skip_vimgrep_pat(p, &reg_pat, NULL);
 			    if (p == NULL || *p == NUL)
 				break;
@@ -5928,8 +5935,10 @@
 	    cmd = USER_CMD_GA(gap, i);
 	    a = (long)cmd->uc_argt;
 
-	    /* Skip commands which don't match the requested prefix */
-	    if (STRNCMP(name, cmd->uc_name, name_len) != 0)
+	    /* Skip commands which don't match the requested prefix and
+	     * commands filtered out. */
+	    if (STRNCMP(name, cmd->uc_name, name_len) != 0
+		    || message_filtered(cmd->uc_name))
 		continue;
 
 	    /* Put out the title first time */