Create a code collection which has mirrored users. When a version of the object is compiled to the mirrored user and then some changes are made, then when an 'undo checkout' is done, Toad recompiles in the original schema instead of the mirrored schema.
WORKAROUND
None
STATUS
This issue is fixed in Toad for Oracle 12.0. This version can be downloaded from the downloads section of our website, which you can access by clicking here.