Expand a visual selection in the other direction

Question

Sometimes I have selected a visual selection with, for example, Vjjjjj, only to realize later that I should have started the selection one line higher. However, pressing k simply decreases the lower range of the selection rather than moving the entire selection up one line.

Here's a visualization (ha, ha), where the bolded lines are the ones I have selected:

Do not select this line
Do not select this line
Select this line!        
Select this line!        <-- I pressed V here...
Select this line!
Select this line!
Select this line!
Select this line!        <-- ... and moved to here. But I should have started my
Do not select this line      selection one line higher!
Do not select this line

How can I extend a visual selection by moving its starting point in the other direction? If this is not possible, is there any way to add a mapping in my .vimrc that enables me to do so?

Answer 1

You can use the o command, from :help v_o:

Go to Other end of highlighted text: The current cursor position becomes the start of the highlighted text and the cursor is moved to the other end of the highlighted text. The highlighted area remains the same.

So when you have finished selecting the lines you want press o, the cursor will move to the beginning of the selection and you can select the line before by pressing k.