Better permissioning for "Create content" menu item

I'm attaching a patch with a workbench content creation access function that checks to see whether users have permission to create content before displaying the tab.

Hi stevector. Yes, that's the message I'm seing. Yes, I do have the "access workbench" permission assigned to roles that don't also have permission to create any type of node. I'm building a job postings website in which one user role ("administrator") is responsible for initial creation of unpublished job nodes, which are then sent to other users with the role of "content editor" to actually enter the details about the job, after which another user role ("approver") is responsible for final review and publishing the jobs. Each of those roles therefore needs to be able to use the dashboard, but only one of them needs to be able to create new job nodes.

For users who don't have permission to actually create any news nodes, the "create content" tab is unnecessary and possibly confusing, which is why I think my patch improves the UX.

Hm, that all makes sense. I didn't realize that _node_add_access() existed. I'm not sure how to modify my patch so it plays well with hook_workbench_create_alter(). Maybe there could also be a hook_workbench_create_access_alter() function which enables modules that implement hook_workbench_create_alter() to define their own permission conditions?

Upon further consideration, I realized that hook_menu_alter already provides a way that modules can define their own permission conditions, so a hook_workbench_create_access_alter() function wouldn't be an improvement. However, I've defined a hook_workbench_create_access() which lets modules add additional permissions to the list of user permissions that would enable the Create Content tab. I've added a usage example to workbench.api.php.

I also took a stab at a Page Manager task plugin for admin/workbench/create, modeled after the myworkbench.inc file that already exists. Warning: I've never written a Ctools plugin before, so I'm not 100% sure I did it right.