Entering Unicode characters in Linux

Hold down the [shift] and [control] keys while typing “u” and the hex values of the Unicode character you wish to enter.

It works in:

• Chrome
• Gnome-Terminal
• Gedit
• Firefox
• LibreOffice
• Telegram
• Nautilus

It doesn't work in:

• Netbeans
• IntelliJ IDEA

I'm running Ubuntu 15.04 64bits.

found here