missing right Alt - remapping xmodmap

Now I've got small keyboard with no right Alt key (AltGR). I need to remap other key, preferably right Crl key, to simulate right Alt. I need to use right Alt to put my national characters in normal way (Alt_R + some letters). That is hard. The only thing I can achieve is by command xmodmap -e "keycode 105 = ISO_Level3_Shift" Than I have these character - BUT ONLY IN THE TERMINAL WINDOW. In Gnome enviroment (word processor, emails) it doesn't work. It still acts as typical control key. my xmodmap is Code: shift      Shift_L (0x32),  Shift_R (0x3e) lock        Caps_Lock (0x42) control    Control_L (0x25),  ISO_Level3_Shift (0x69) mod1        Alt_L (0x40),  Alt_R (0x6c),  Meta_L (0xcd) mod2        Num_Lock (0x4d) mod3      mod4        Super_L (0x85),  Super_R (0x86),  Super_L (0xce),  Hyper_L (0xcf) mod5        ISO_Level3_Shift (0x5c),  Mode_switch (0xcb) I use ISO_Level3_Shift because using Alt_R does not work. Can you help me?

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