Issue Viewer See All of Jet Reports but Not Editable
The functionality discussed has been added to the latest released version of Jet Reports 4.0.7 as follows.

Introducing Viewer Editable Worksheets
If you would like to design a report that Viewers can use without locking any of the worksheets, you can instead convert the workbook to values.  You do this by placing Auto+Hide+Value in cell A1 of any worksheet.  Upon doing this, all Jet Reports formulas will be converted to values while all other Excel formulas will remain intact. The Jet Reports formulas can be restored by selecting Jet/Design.  Please note that this is only applicable if you are using Excel 2003 or later.

We designed most of the sample workbooks for use by report Viewers so you can see examples of how to do this.

The long term solution will be to implement the latest version of Jet Reports for all designers/viewers.  This has no impact on the server or data.  This can be done reliably without impact to the existing structure.  This only applies to Excel 2003 and is a requirement prior to using this feature, but not a requirement to using the latest version of Jet Reports as a whole.

I trust this answers your concerns and thank you for your comments.  We will be planning for the upgrade in the coming weeks.  Please advise if you wish to proceed with the Jet Reports update immediately to resolve your current pain.

A short term workaround for a viewer would be to highlight the data on a worksheet, copy the data, open a new workbook, right click and paste special values only.  This should allow for altering and playing with the data.