The UseSystemPasswordChar property has precedence over the PasswordChar property. Whenever the UseSystemPasswordChar is set to true, the default system password character is used and any character set by PasswordChar is ignored.
When the TextBox is in password mode because PasswordChar, UseSystemPasswordChar, or ReadOnly is true, the TextBox is in restricted mode. In this mode, the ImeMode is disabled, but the current ImeMode is cached so that it can be restored if the TextBox ever becomes unrestricted. Toggling the ReadOnly is a common scenario. The ImeMode is shadowed while the control is in restricted mode. From the designer perspective, the ImeMode value shown is the actual value.
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)