No switching of panes or long presses each character is typed with a single gesture.

All the characters you might need are available on a single screen as well as control alt escape and many others.

Several characters are displayed on each key. Get the one in the middle with a press and the ones in the corners by sliding your finger.

Like any other keyboard app you will need to activate it in the system settings to be able to use it.
This can be found in the System Settings > System > Languages & Input > Virtual keyboard > Manage keyboards.