OS: Ubuntu MATE 18.04.1 LTS (Bionic Beaver) 32-bit
Window manager: Marco; it is MATE Desktop Environment default window manager. MATE Marco is a fork of GNOME Metacity.
Lazarus: 2.0 RC2 gtk2
User of CudaText and Lazarus IDE:
>>I use the key combination AltGr+<key> to insert special characters into text. This combination works system-wide on Linux Desktop, however, it does not work in CudaText (and Lazarus).