ediff-before-setup-windows-hook is a variable defined in `ediff-init.el'.
Its value is
nil
This variable may be risky if used as a file-local variable.
Documentation:
Hooks to run before Ediff sets its window configuration.
This hook is run every time when Ediff arranges its windows.
This happens each time Ediff detects that the windows were messed up by the
user.
You can customize this variable.