You mean in Presentation mode? Don't think zoom works there; on my desktop zoom has no effect. Presentation mode is a waste of time IMHO on the N900, and my time is better spent improving the Fullscreen view.

At least when I switch from non-fullscreen mode into Fullscreen mode, the zoom setting is retained.

Grab -maemo1 from extras-devel. I uploaded an update yesterday which is still not finished, but is a damn sight better than maemo0.

Quick list of shortcuts:
Ctrl-O - Open;
Shift+Enter - Properties;
"Quick Page Down" - Ctrl+Down;
"Quick Page Up" - Ctrl+Up;
Show/Hide Side Pane - Ctrl+Z;
Toggle Fullscreen - Ctrl + Enter;

Toggle special mode: Ctrl + Space

In special mode:
Volume Up: Next page
Volume Down: Previous page

In "normal" mode:
Volume up: Zoom in
Volume down: Zoom out

If special mode is off and you're in Fullscreen mode, you can tap the top and bottom of the page to have it go down.

"Fn"+Enter - Bring up the menu

Except for a few that I removed, because they conflicted, the rest of the shortcuts should be the same.

@mtjioe

Qt is not my cup of tea, sorry.