Q: It seems that the selected item in the Font menu sometimes (but not always) changes when I change keyboard layouts, and vice versa - why?
A: Here we go - the "script ranges". Russian script works in mysterious ways - well, not really, but it sounds good. If you choose a keyboard layout which is in the Russian script range (on your Keyboard menu below the gray separator line), the system will attempt to switch the default font to one of the fonts which are in the Russian script range also (those are Apple Standard Cyrillic and the ER series of fonts). Vice versa, if you choose a font in Russian script range after working in Roman (default in U.S. systems) script, the system will try to switch the keyboard layouts for you as well. You have to play with it to see the effect.
If you examine the keyboard layouts from my shareware package, you'll notice one layout designed for Apple Standard Cyrillic and it is in the Russian script range, appearing below the separator in your Keyboard menu - that's because, as mentioned before, Apple Standard Cyrillic fonts are in that range. However, you will notice 2 keyboard layouts designed for use with KOI8 fonts - one in Roman script range (appears above the separator line in Keyboard menu) and one in Russian (appears below the separator). The explanation is simple: Dan Chirkov's "KOI8-Terminal" font is in Roman script range and the KOI8 fonts in ER series are in Russian script range. So, if you intend to use "KOI8-Terminal" font and would first go under Keyboard menu and choose my keyboard layout for KOI8 fonts below the separator line and then select "KOI8-Terminal" font from the font menu in your application, you'll notice he keyboard layout automatically changing back to U.S. again - that's the power of Script ranges. The moral of the story - use my KOI8 layout found above the separator line for "KOI8-Terminal" and everything will be fine.