Add option to use single click to open files instead of double click.

[yuckdevchan]

I looked for this option but couldn't find it.

This is an option in many environment such as KDE and GNOME. It's useful because it means you don't have to double click all the time. Instead of clicking to select a file, you select by checking its box or selecting it by drawing a selection rectangle(?) through it. I would love to have this as an option.