have chained dead keys
   input two or more characters with a non-printable key or a dead key sequence
   input a character even when a dead key sequence failed to compose a character

Since Firefox version 52, text input with many Chinese environment traditional input method have problem when typing combo keys. using Shift + numbers or symbols, or type space key, etc. maybe is cause by this change " Improved text input for third-party keyboard layouts on Windows. This will address some keyboard layouts that have chained dead keys input two or more characters with a non-printable key or a dead key sequence input a character even when a dead key sequence failed to compose a character " Please fix this issue or make adjustable preference to disable this function. Best regards.