Hotkeys/Send keys: fix disallowing certain key names such as =A:: whi…

…ch previously wrongly was just understood as =

only first character used, should have rejected
ref #26

src/run/display/x11.cr

@@ -186,6 +186,7 @@ module Run
 				@@ahk_key_name_to_keysym_cache[key_name] = lookup
 				return lookup
 			end
+			return nil if key_name.size > 1
 			char = key_name[0]
 			return nil if char >= 'A' && char < 'Z' || char >= 'a' && char <= 'z'
 			# This fallback may fail but it's very likely this is the correct match now.