Need ability to keep Item open in current display in current collab area step (after uses clicks on an exit value button, but *without* adding an error message)

When editing a single item in a step in a collab area,

- User clicks an "Exit Value" button

- MDM CE automatically saves the item

- If there is an error during the save (if one or more of the attributes have an error) then the item stays open on the display (and is not automatically closed)

- If there are no errors during the save, then the item automatically closes (because MDM CE assumes the item is moving to the next step in the Collab Area)

     - We want the ability to STOP this automatic closing of the current window because we "know" the item is going to stay in the current step

We want the ability to "flag" an item as "staying in the current" step during the Post Processing - but *without* adding an "Error Message" to an attribute.

Currently - in "Post Processing" - we can register an error against an attribute, and that will both:

- keep the item in the current step

- AND keep the item displayed on the screen (keep the current window open)

But - if we don't have an error (but still want to keep the item in the current step) - then this is what happens:

- Post Processing does nothing special

- Because MDM CE thinks everything is done with the current item, MDM CE closes the item in the display

- Code in the "out" script for the step keeps the item in the current step (removes the item from the step transition)

- So - the item stayed in the current step (because it was "stopped" in the "out" script of the step) - BUT - to the user - it looks like the item left the step because the display closed the item in the view/edit window

That's the scenario we have.  In Post Processing we already know we want to keep the item in the current step.  We already know that logic in the "out" script is going to stop the item from leaving the current step.  Because we already know the item is going to stay in the current step, we want to *keep the display open*.  *Don't close the display of the current item*.  But we don't want to "scare" the user with a Red-X error message.   And - right now - the only way to keep the display "open" for the current item is to report an error and scare the user with a Red-X error message. 

The real-world scenario causing this is:

- We have a "Validate" button defined as an exit value for various steps

- When a user clicks "Validate", we run various, extra custom validations (and keep the item in the current step)

- If the validations find errors, the errors are reported (using the standard error reporting mechanism to show errors against Attribute Instances in the display) - so the item both stays in the current step and the user sees the appropriate error messages on the screen

- If the validations do not find any errors, then there are no errors to report - BUT we still keep the item in the current step.  When the user clicked "Validate" - they don't want the item to leave the step.  They want it to stay in the current step AND they want the item to stay "open" in the current display.  And that's the problem.  We can easily keep the item in the current step (just remove the item from the "step transition" in the "out" script of the step), but we don't have a way to keep the item "open" in the current display without reporting an error against one or more attributes.