tell application "TextWrangler"
if (display magnification of text window 1 is greater than 3.9) then
set display magnification of text window 1 to 4
else
set display magnification of text window 1 to ((display magnification of text window 1) + 0.1)
end if
end tell
tell application "TextWrangler"
if (display magnification of text window 1 is less than 0.6) then
set display magnification of text window 1 to 0.5
else
set display magnification of text window 1 to ((display magnification of text window 1) - 0.1)
end if
end tell
tell application "TextWrangler"
set display magnification of text window 1 to 1
end tell