This command offers you some new practical improvements to manage guides.
You can accede to it via
-> .Guides options of the Image submenu
Options
This option removes all guides from image.
This option opens a dialog where, after selecting the Direction of the new guide, you can set its Position more precisely than by using click-and-drag. The coordinate origin is the image left upper corner.
In these option, guide position is a percentage of the image Heigth/Width.
This option places four guides for upper and lower, left and right limits of the current selection. Nothing happens if there is no selection.