Problem:

There are situations where a user wants to paste multiple rows,
but is unable to do it intuitively.

Repro:

Open a spreadsheet
Click and hold on the row 1 "button" at the left end of the row.
Drag to select rows 1 through 5.
Right-mouseclick -> Copy
Click on the row 10 "button" at the left end of row 10 (this selects row 10).
Right-mouseclick -> Paste.

Result:

    Unable to paste : destination does not have an even multiple 
    of source rows (1 vs 3)
    Try selecting a single cell or an area of the same shape and size.

Expect:

Either we should simply paste the data, as requested, overwriting
previous data, or perhaps we should prompt the user with a warning
saying:  "Do you really want to overwrite the current data?"
If we implemented the warning, we could include an opt-out checkbox
to allow the user to have that warning suppressed in the future 
and simply perform the data overwrite.

Note:  I would expect this to work as well, if I had performed 
a Cut -> Paste rather than a Copy -> Paste.

Also, if we implement this feature, we'd obviously do it for 
columns as well as rows.