The quick help of Unity (long press on the Super button) shows that Switch windows of current application can be triggered by Alt+Grave keyboard shortcut. What is Grave?
Here it is:
This is usually the button immediately above the TAB on most keyboards.
For my keyboard - grave is actually correctly known as the ` key - grave is also known as the back-tick.
In my travels I have seen the Ubuntu "key above the tab" to actually be the § or º. I'm sure there are many other similar characters on peoples keyboards.
Depending on your locality if you press and hold the SUPER to display the overlay, you should see the equivalent Grave key for your locality
(thanks Javier Rivera)
For my keyboard combination - ALT+` - gives you this switching capability (cycle through the windows group):
To use this key combination - let go of the grave without letting go of Alt and then repress grave to cycle through the windows group.
tilde | ˈtildə | noun
ORIGIN mid 19th cent.: from Spanish, based on Latin titulus.
macron | ˈmāˌkrän; **ˈmak-; ˈmākrən | noun
ORIGIN mid 19th cent.: from Greek makron, neuter of makros ‘long.’
Good question yossile (+1)up.
To my knowledge, the dictionary quote above is "not accurate/adequate", since one can find