MacTricks
In Excel, if I get the margins error, In the layout tab set the "Size" to US Letter.
The dock can't be completely disabled because it's responsible for some background system stuff, but you can delay its appearance with:
defaults write com.apple.dock autohide-delay -float 2; killall Dock
"-float 2" has units of seconds.
defaults delete com.apple.Dock autohide-delay && killall Dock
Sets the dock back to normal.