created an attachment (id=166282)
screenshot

description:
"restore properties from the original library item" is disabled for table extended from library after change group key.

build number:
2.6.0.v20100428-0630

steps to reproduce:
1. new a library containing a table binding to the data set, with a group.
2. new a report design extends the table in the library.
3. change the group key for the table in the report, check the "restore properties from the original library item" button on the top right of property editor view.

expected result:
"restore properties from the original library item" is enabled.

actual result:
restore is disabled (see the screenshot). 

error log:
n/a
need mode to verify the check logic.
the key is set on the group. so, it cannot be restored by choosing table. restoring property is for each element, not including nested elements.
see above comments.
verified in build (2.6.0.v20100506-0630), closed.