When the dialog is opened for the first time, the focus normally lands on the channel name edit field. But if it is disabled, e.g. in MOD/S3M, the focus simply gets stuck and breaks the Esc key.
Upon subsequent openings, the focus always lands on the dialog itself. In this case it's at least possible to move it to the first control by pressing Tab.
Keyboard focus should always go to the first active control regardless of what it is on every opening of the dialog.
Additionally, the accessible dialog title is never updated when navigating between channels.