tweaks: judge from the key code itself whether it is a Meta keystroke

src/global.c

@@ -419,7 +419,8 @@ int the_code_for(void (*func)(void), int defaultval)
 	if (s == NULL)
 		return defaultval;
 
-	meta_key = s->meta;
+	meta_key = (0x20 <= s->keycode && s->keycode <= 0x7E);
+
 	return s->keycode;
 }
 

src/winio.c

@@ -1689,7 +1689,7 @@ int get_mouseinput(int *mouse_y, int *mouse_x, bool allow_shortcuts)
 					const keystruct *shortcut = first_sc_for(currmenu, f->func);
 
 					put_back(shortcut->keycode);
-					if (shortcut->meta)
+					if (0x20 <= shortcut->keycode && shortcut->keycode <= 0x7E)
 						put_back(ESC_CODE);
 					break;
 				}