One of my customers modified the mapping between Account and Contact and from that point forward, the received the following error message ( DevErrors are turned on ) when attempting to add a new Contact to an existing Account:

Now that was rather confusing because it only happened if you had an Account open, selected Contacts, [...]

One of my current projects required me to create a new Entity record when the user pressed a button that had been added to the toolbar.  The two Entities were related so data is automatically copied from the Parent record to the new Child record.
The only problem I ran into was in making sure that [...]