calc functionality question

users
#1

Hi
Ive just been using calc, i had a few cells in a column selected intending to fill down but unintentionally did something else, dragging somehow with the mouse as if moving the cells vertically. The text in the cells did not move, instead it vanished and i was left with a bold double outline around the cells that would have been the destination if the drag had moved the cell contents. Ctrl-z restored the cell contents in their original position, but the heavy black outline temained around the 'destination' cells and did not disappear even when selecting a completely different cell. It remains even after i perform the fill down with the cells that i had originally intended.
I have a number of related questions:
a) what does this heavy outline signify, what is its purpose? It doesnt seem to be involved with input in any way as it remains when a new cell is selected and that new cell appears to have the focus as normal.
b) what did i do to get it - if i acctually want this at some future date, how do i go about getting it?
c) how do i cancel it, and get rid of the heavy outline?

Im using 1:5.2.2-0ubuntu2.1 (which i realise is a bit old but updating will have to wait until i have internet access on my computer to upgrade)

Thanks
/Gary