if its text you want outlining, the best way is to have the outline colour and the inside colour selected when you add the text. but using the line tool to go round the edge usually works then just merge it to the layer you want or allternatively use the drop shadow with opacity at 100 and blur at 0 and add it to each corner (4 shadows and merge it together)
eg, vertical 2 horizontal -2 (bottom left corner)
then vertical 2 horzontal 2 (bottom right corner)
then vertiacal -2 horizontal 2 (top right corner)
and vertical -2 horizontal -2 (top left corner)
this way you have shadow with a sharp edge all round the text/image.
hope it helped.