Restrict Ability to Submit Ideas for a Product

As a Product Manager, I would like to control which products can have ideas. There are a couple of way to provide this capability: disable ideas on a product-by-product basis, restrict ability to create ideas within the portal by user or role, remove ideas from the ADD menu.  We can suppress Ideas from navigation but a user can create an idea by clicking the "+" (ADD) menu in the upper, right-hand corner.  This is particularly problematic because it seems to default to whichever product a user is viewing and if they don't choose another product when submitting the idea, it may definitely end up in the wrong place and they won't see any of the custom fields intended for all ideas.

Users don't always understand which products an idea fits into.  When an idea is created, the reference ID contains the code for the product and if the idea is created in the wrong product, the reference ID forever indicates something that's not true.  I created a product specifically for ideas (having a prefix of IDEA) and the ideas remain there until they are promoted to features.