I have found, and proven by creating a new component that if you have a front end collection and you cancel a backend item, the front end collection is shown after the cancel.

Steps to replicate (item to prove on my project is called 'Test' for admin)

1) New project
2) New simple table (string and published)
3) Create backend collection, save default, create basic grid
4) Create backend end item, save default, add basic fields.. leave toolbar
5) Test - Create a new item and CANCEL, goes back to backend collection

now

6) create a front end collection, save default, create grid
7) create a front end item, save default, add fly info

test

now in BACKEND, create an item.. but CANCEL now you go to what appears to be the frontend screen displayed in the backend.. no buttons etc

I have only tested this in SANDBOX, I have not downloaded and tested in default install so not sure if its a sandbox or component error.

This problem was first discovered when entering data in one of my proper projects.

Version Joomla 3.0
Embedded framework
Include dataset
Formstyle - exploded
Features - all features
DB - Table
40 seconds

It appears to be adding a layout=modal.. delete that the view is fine.. however the fault only seems to occur when there is a frontend view, certainly in the tests I have done anyway

This is already fixed in my hands.
The upgrade is coming soon.

Fixed

Most certainly is! Good job (as usual)