Qt Interface preferences disable "enqueue" option even when it's meaningful

In the Qt Preferences, Interface Settings page:

• The option "Enqueue items into playlist in one instance mode" is disabled (made unchangeable) whenever "Allow only one instance" is unchecked
• However, if "Use only one instance from file manager" is checked, then the setting of "Enqueue items into playlist in one instance mode" is meaningful even if "Allow only one instance" is unchecked:
  • If "Enqueue..." is unchecked, double-clicking a video in the file manager will start it immediately, even if another video is already playing.
  • If "Enqueue..." is checked, double-clicking a video in the file manager will silently add the video to the playlist without affecting any playing media.

Because of the dependent nature of the enqueue option, enabling it for file-manager-only mode requires checking "Allow only one instance", checking "Enqueue...", and then unchecking "Allow only one instance" again.