Suppose that I have already selected some text in the current buffer.
Is it possible to select another stretch of text, while keeping the previous selection (and so on)?

**Added**: One motivation for this functionality is as follows:
Assume that I have some text that looks like this:

```
paragraph 1 ...

paragraph 2 ...

paragraph 3 ...

paragraph 4 ...

paragraph 5 ...

```

I would like to remove some paragraphs (e.g. 2, 4 and 6) and insert them before paragraph 1.