Tip: IntelliJ IDEA : Do not want unlimited whitespace at the end of each line

File menu -> Settings -> Editor -> Virtual Space and uncheck 'Allow placement of caret after end of line'. 

Also uncheck the other options in the Virtual Space panel.

If you want to remove trailing whitespaces, you can do
File menu-->Settings --> Editor --> Strip Whitespaces on Save   to either "All" or "ModifiedLines".

Tip: Mac OSX: Start IntelliJ with sudo permissions

There may be instances where the code you are developing is binding to a particular port that is lower than 1024. So you will not be able to bind to that port.

You will see something like a SocketException : permission denied.

If you are sure that this is temporary and you are developing on your Apple laptop, then do the following in a terminal window:

$>cd IntelliJ\ IDEA\ 12\ CE.app/Contents/MacOS/

$> sudo ./idea

Now IntelliJ is running with sudo permissions.

WARNING: This is a sensitive operation. Do not try it on Apple based servers or production environments.