The process for "Insert->Sheet From File..." could be improved: In the "Insert Sheet" dialog, the "Name" field should not be restricted to "New sheet" but also be active for "From file" to enable the user to assign a name for the imported sheet.
*** Bug 67481 has been marked as a duplicate of this bug. ***
I can confirm this behavior with LO 4.0.5.1 (Win7 32bit). Should be a valid enhancement request that could make such function better.
*** Bug 154598 has been marked as a duplicate of this bug. ***
Field was already greyed out in OOo 3.3, so marking as inherited.