There is truly only one way to reverse this problem – if it truly is a problem for you. I was frustrated that whenever I’d receive an alert from iCal, I’d get a popup that would then proceed to open Mac Mail, which I don’t use.

This is a nasty workaround, but basically sets a permission on the Mail application so that it is no longer readable or executable.

Firstly, to turn off the Mail notifications:
sudo chmod 000 /Applications/Mail.app/Contents/MacOS/Mail

Secondly, to re-enable:
sudo chmod 755 /Applications/Mail.app/Contents/MacOS/Mail

On Mac OSX, to change the Save As dialog to ensure that it always expanded, you can run a command from Terminal that will permanently change the setting. I prefer to have a Windows style Save dialog that gives me a list of all of the files and folders, as opposed to the default in Mac OSX that shows just the last/default directory.

defaults write -g NSNavPanelExpandedStateForSaveMode -bool TRUE

When .DS_Store makes an unwanted arrival on your desktop, use the command below to get rid of it.

 defaults write com.apple.finder AppleShowAllFiles -bool false

For some reason, my Mac OSX desktop icons disappeared earlier and my Finder was also completely empty.

To fix this, run this from Terminal, and not as a superuser.

defaults write com.apple.finder CreateDesktop -bool true
killall Finder