Both

If I copy lines from Notepad I would expect it to paste lines into the studio

If I could copy a column from Notepad I would expect it to past a column into the studio

i.e. the behaviour of the Paste operation should be dictated by the last Copy operation not the last Paste .... however typing this I can see the challenge the last DF copy was a column and it probably has no way of knowing what type of copy the last external application used