commit https://github.com/vim/vim/commit/5f1fea28f5bc573e2430773c49e95ae1f9cc2a25 Author: Bram Moolenaar <Bram@vim.org> Date: Fri Sep 25 19:12:22 2015 +0200 patch 7.4.882 Problem: When leaving the command line window with CTRL-C while a completion menu is displayed the menu isn't removed. Solution: Force a screen update. (Hirohito Higashi)

--- a/src/edit.c
+++ b/src/edit.c
@@ -3903,6 +3903,12 @@ ins_compl_prep(c)
 		showmode();
 	    }
 
+#ifdef FEAT_CMDWIN
+	    if (c == Ctrl_C && cmdwin_type != 0)
+		/* Avoid the popup menu remains displayed when leaving the
+		 * command line window. */
+		update_screen(0);
+#endif
 #ifdef FEAT_CINDENT
 	    /*
 	     * Indent now if a key was typed that is in 'cinkeys'.