I wrote a small keycode display script to help me find the codes for the keys not listed in the manual's ASCII table. When using it, I discovered a problem, which limits the functionality of my interface.
The keycode for PgUp (regular, not numeric) is 380, which is identical to Down arrow.
This means that
1) It's impossible to use PgUp/PgDn (e.g. to scroll a whole inventory or save list page) while also using the arrows (e.g. to scroll just one line up/down).
2) That PgUp and the arrow down key have the same functionality despite their opposite meanings. A player discovering this could find it confusing.
3) It also seems incosistent that there are two keycodes for PgUp and PgUp numeric (380 and 373), while the keycodes for PgDn and numeric PgDn are identical (381).
I'm aware that this issue may be Windows related and not internal to AGS, but I hope there's some kind of workaround.
Ah yes, keys that aren't listed in the ASCII Code Table have no guarantees about their keycode numbers and may well overlap keys that are listed.
I'll make PgDn and PgUp official and supported, and allocate them a proper number.
Edit by strazer: Done since AGS v2.71 Beta 3
Thank you very much CJ!