Delete button not visible on not published nodes

Core Node module's node_form function is calling node_access('delete', $node) directly to determine whether to display delete button. node_access returns FALSE for a couple of reasons:

1. node_access first calls node_content_access which returns NULL because with Workflow we are intentionally not permitting user_access 'delete any ...' or 'delete own ...' permissions (allowing these permissions would override Workflow access permissions which would mess up the user role access at different stages in a node's workflow).

2. node_access will not check access grants for nodes where status = 0 i.e. unpublished nodes.

node_access ideally should be replaced by module_grants_node_access function which acts precisely to combat issue number 2 above. However, since it is called directly the only way to do this I'm guessing would be to hack core. In addition, node_form does not make use of '#access' variable for the delete button, rather the entire delete button array is excluded if node_access returns false.

So the solution I used was to basically re-add the delete button if module_grants_node_access returns true for the node delete operation, for the current user:

if (!isset($form['buttons']['delete']) && module_grants_node_access('delete', $form['#node'])) {
  $form['buttons']['delete'] = array(
    '#type' => 'submit',
    '#value' => t('Delete'),
    '#weight' => 15,
    '#submit' => array('node_form_delete_submit'),
  );
}

I originally added this to module_grants form alter, because I needed it to happen before module_grants made its adjustments to the delete button text (and I didn't want to create a new module just for one form_alter). In module_grants 6.x-3.5 form_alter has been moved to node_tools module.

Since it is the workflow module that dictates that we are not using the 'delete own' or 'delete any' permissions then perhaps it would make sense to add it to workflow module. However, presumably any access modules that provide alternative 'delete' access/grants are going to run into this "missing delete button" problem, so I'm thinking it is still a good candidate for module_grants/node_tools form_alter instead.

Patch that I'm using for node_tools 6.x-3.5 attached, apply to module_grants folder.

See also, http://drupal.org/node/592164 where alternative solution is provided, i.e. to hack core and add module_grants_node_access function call to core node_access function.