Hi Grace

'SelectionColor' is the color the bar in the pageandlayer gallery displays for selected item[s] [edit - ie items shown as selected in the gallery so it includes 'page' and 'layer' entries as and when selected not just items selected on the workspace]

'DeactivationColour' is the color the text in the gallery turns for an item that is locked and/or hidden

'StripeColor' is the color given to every alternative entry in the gallery, opposing to the background color [which default is white] so as to make the entries easier to determinate [see/count/whatever] [edit - this is of course overidden by selection color as appropriate]