Copy the image as a whole to a new image.(no extra layers,just the entire menu as a single image)(select all,copy merged)
On your new image Use the selection tool and select the part of the image you want to use for the User Pane and right click ans goto new layer via cut.
Repeat with all the pieces you need and you have each section on a separate layer
Open SS and hit edit for the piece you want to change...place the appropriate layer from your cut document into the section you are working on and delete the original image layer.That leaves only your new layer.
You will have to resize the image you are replacing to the new images size first.
Save it,but leave it open in case you want to change it.
Go back to SS and set your margins for tiling or stretching.
Do all the others and you will be ready to do the More programs arrow,Item mouseover and logoff buttons.
git 'r' done