How do you select a coroner on a volume?

Yes, I know this is probably very simple but I cant find it. I read the documentation, watch tutorials and cant find it mentioned. In UE3 you would right click the point to select it. I just need to create a Trigger volume and use the scaling tool to increase its size to the right, but leaving the selected point anchored where it is. :frowning:

in the ‘modes’ pane, select ‘edit geometry’ and then click the corner. you can also select whole faces or edges this way too.