Choosing Browse > Select leads to these choices:
Return will cancel the choice.
The others put you in 'select mode' where the cursor changes to a question mark. Move to a word you are interested in selecting and pause over it. The selected area around that word will be highlighted temporarily in reversed colors. Selecting a sentence may not always give you what you expect. Determining where a sentence begins and ends is not an exact science. The contents of the selected area will be put in the message area. This enables you to copy the selected text from files, books, and email for including in email or for inserting in other files.
Another effect of making a selection is that the text will be put on the clipboard. You can then paste it into other applications. Any text that is 'cleared' (with Clear) will also be put on the clipboard.