Customizing font-lock-mark-block-function in minor-mode

[Tobias C. Rittweiler]

Hi all,

What is the best way for a minor mode to customize the value of
`font-lock-mark-block-function' of its major-mode?

Adding a hook to the major-mode-hook which modifies this variable is
later overwritten by the binding in `font-lock-defaults'.

Adding a hook which modifies `font-lock-defaults' appropriately is not
very easy without making explicit assumption of the major-mode's
particular format of `font-lock-defaults'. These assumption may break
under my feet in the future.

What am I missing?,

  -T.