Showing the lookup field only...

You can have a field and apply a lookup on it. If you set this field to a label field than it will display the value and the lookupvalue. Now in many cases users might want to display the lookup only and not the key value. I tried to set css to 1 pixel, but that’s completely ignored. A checkbox with the primary question to show the primary value or not would be great. Another option would be the select drop down, but if you select this field you cannot set it to read-only. But in that case the keyvalue is not shown, only the lookup (which is what i want).