set appname to "Firefox"
tell application appname to set nam to name of front window
tell application appname to set boundsrect to bounds of window nam
set newbds to {(item 1 of boundsrect) + 10, (item 2 of boundsrect) + 10, (item 3 of boundsrect) + 10, (item 4 of boundsrect) + 10}
tell application appname to set bounds of window nam to newbds