How to use WinMerge with "Github for Windows"

I use "Github for Windows" as the git client (and use it with an enterprise github server). Is it possible to configure using WinMerge to be used with this client? I have not seen a setting for setting up any GUI diff tool for that matter.

In C:\Users"name of user" folder open file .gitconfig and write

[merge]
tool = winmerge
[mergetool]
prompt = false
keepBackup = false
keepTemporaries = false
[mergetool "winmerge"]
name = WinMerge
trustExitCode = true
cmd = "\"C:/Program Files (x86)/WinMerge/WinMergeU.exe\" \"$LOCAL\" \"$REMOTE\" \"$MERGED\"     >/dev/null 2>&1"
keepBackup=false

Then,

• restart github desktop,
• in left pannel :
• select repository :
• right click : Open in Command Prompt.
• When the command prompt appears type: git mergetool

If it doesn't work, try : git mergetool –tool=winmerge