In sys/src/9/pc/kbd:447 a `Latin' key press will turn on a key
collecting mode to allow the input of characters as described in
keyboard(6).

Cyrillic characters may be entered, for example, by a sequence
Latin + @ + Z + H, resulting in Ж. On a german keyboard layout
@ is only accessible using Altgr.  Unfortunately, Altgr cancels the
collection mode started by pressing `Latin', so on such a keyboard I
cannot enter cyrillic letters this way.

If I remove the line
			kbscan.collecting = 0;

from the Altgr case, I can enter cyrillic letters using the Latin + @
sequence.

Likely there has been a reason to have Altgr cancel the collection of
keys (I don't know which), so this change probably is not acceptable.