I found out the solution myself!

Drain the note2 until it turns itself off.
Restart and the writingstyle-option will popup, press ok.
That's it!

Probably it resets certain values in some kind of way.

Recently Opera started operating strange.
I have several devices with the same issue.

Problem 1: Normally when tapping a textbox the keypad would appear automatically.
Now it only appears after tapping twice.
Problem 2: normally the keypad closes by tapping once beside the textbox but now it stays visible.
Only by going back with the bottom-right-back arrow of my Note2 it disappears.

*other apps are functioning normally

opera mobile version 12.10
Samsung note2 n7100
Android 4.4.2