The Login window can't show correctly in the right of password bar.
(If I choose "English for non-Unicode programs" in the Language of control panel, it can show correctly. But I can only choose "Chinese" in Simplified Chinese environment.)
By the way, I don't know what is the purpose of this button.
I currently don't know what causes this problem but it has been reported already:
The purpose of this button is to show/hide the password on the left, i.e. show it as plain text or hide it with asterisks.
Sure, it's same in Simplified or Traditional Chinese environment.
Hope next version can fix it.
Perhaps an unicode version is more perfect? I know this can't become true very soon. Do you have this plan?