I can’t get this to work. (I’m on version 6.8.7.)
I have a decent workaround, though - the page I’m working with overrides a Salesforce object called MedRec__c. So, if the page is displayed primarily, the parameter ‘sfdc.override’ contains ‘MedRec__c’. If the page is displayed in a popup with a page include, then the parameter ‘sfdc.override’ does NOT contain MedRec__c. I can use this to control whether or not my “Save and Close” button is displayed.
It seems that the render conditions access the URL I see in my browser and not the query string in the page include.
