Problem description:
Some users create a .csv file with Calc and add a second sheet. 
They spend hours working on these sheets and 
then save one of these sheets as "csv". Then they close Calc. 

Expected behaviour: 
After "saving" and "saving as" users expect to reopen the complete spreadsheet,
including formatting and all (multiple) sheets.

Unexpected behaviour: 
When they reopen Calc and reload the .csv-file, 
only the active sheet at the saving point will be reopened. 
Changes to other (inactive) sheets in the spreadsheets will be lost.

For an example and forum-discussions to this topic visit:
http://www.oooforum.org/forum/viewtopic.phtml?t=60008&highlight=

Enhancement request:
Most of the problems by misunderstanding, data-losses, and ill-will 
might be avoided if the button "Save As" for limited formats (such as csv) 
would be moved to "File - Export".
This way, a user can never have the impression 
that he correctly saved all the data he is working on. 

- JWR.