Sinclair, cursor, QAOP — in catalog and for going to next/previous file from music player or gfx viewer.
Space, 0 — select file/exit to catalog.
Enter — next file in gfx, msx & text viewer.
F — Filter for file types: All, Basic, Graphics, Music.
Caps Shift + A — fast select "All" filter.
B, G, M — fast select Basic, Graphics or Music filters accordingly.
I — file info. Press again to changedec/hex.
R — run basic and code files.
Caps + R — run with white border.
C — On/off Gigascreen mode in catalog.
L — On/off Quicklook mode. When ON, The Viewer will automatically load preview of a file. That would be handy for browsing, especially if you search something.
S — Open Setup.