Toggle Hidden Files without Relaunching Finder
The trick of switching views worked well in Yosemite but no longer in El Capitan.

I've had to go back to the simple, yet annoying

set newHiddenVisiblesState to "YES"
try
    set oldHiddenVisiblesState to do shell script "defaults read com.apple.finder AppleShowAllFiles"
    if oldHiddenVisiblesState is in {"1", "YES"} then
        set newHiddenVisiblesState to "NO"
    end if
end try
do shell script "defaults write com.apple.finder AppleShowAllFiles " &amp; newHiddenVisiblesState &amp; "; killall Finder"


Rather than the much nicer version which worked before 

set newHiddenVisiblesState to "YES"
try
    set oldHiddenVisiblesState to do shell script "defaults read com.apple.finder AppleShowAllFiles"
    if oldHiddenVisiblesState is in {"1", "YES"} then
        set newHiddenVisiblesState to "NO"
    end if
end try
do shell script "defaults write com.apple.finder AppleShowAllFiles " &amp; newHiddenVisiblesState    

tell application "Finder"
    set theWindows to every Finder window
    repeat with i from 1 to number of items in theWindows
        set this_item to item i of theWindows
        set theView to current view of this_item
        if theView is list view then
            set current view of this_item to icon view
        else
            set current view of this_item to list view

        end if
        set current view of this_item to theView
    end repeat
end tell


Honestly, I'd love this answer to be wrong

BTW, Windows ought to reopen exactly where they were - but not if you have them spread over more than one Space; that's not possible.