FWIW I've fund a workaround using something called
AutoHotkey. I started using it because I wanted to disable the capslock key before I did physical damage to my keyboard. It's been useful for all sorts of other things since...
It can send windows messages to the cleanup display to have it horizontal scroll a page at a time when ctrl + < > are pressed. Like this:
; Page right - Press Ctrl+>
^>::
ControlGetFocus, FocusedControl, A
SendMessage, 0x114, 3, 0, %FocusedControl%, A ; 0x114 is WM_HSCROLL 3 PG_RIGHT, 2 PG_LEFT
return ;
; Page left - Press Ctrl+<
^<::
ControlGetFocus, FocusedControl, A
SendMessage, 0x114, 2, 0, %FocusedControl%, A ; 0x114 is WM_HSCROLL 3 PG_RIGHT, 2 PG_LEFT
Neat I thought. I still have to click on the window to ensure it's the one with focus to start, though I'm fairly sure I could write more script to sort that out too...