I really love jharker proposal.
Some proposed modifications to the proposal

:
- A setting to disable all long presses (for me they are more an inconvenient than an advantage, as they fail too much)
- Put the landscape/portrait mode selection in the system menu (it's a system thing if we do it using xrandr; right now its the viewer that makes the rotation but that is not reasonable -- apps would not be capable of being rotated the way it is now)
Also, I attach a mock up of a possibility of having a one-line toolbar (in the case of showing the pagebar, the "iliad pagebar" would be in the position of the icons -- I've not drawn that in the examples... I was frustrated because of having to draw with the mouse instead of a pen; hope this is enough

).