I know that you can enable those zoom modes editing the options.xml file in this part:

<zoom>
<toregion>0</toregion> <!-- zoom-to-region mode (0 - disabled, 1 - enabled) -->
<offcenter>0</offcenter> <!-- the image region pointed by mouse cursor (when zooming is started) retains its position on screen (0 - disabled, 1 - enabled) -->
</zoom>

however if you enable those options you loose the standard zoom mode...

I'd like to have all the 3 options available from the GUI or from the hotkey menu.
I mean, sometimes you need the standard zoom, sometimes the zoom-to-region and sometimes the off-center zoom...

why not having all of them istead of choosing just one?

OK, we will consider your remarks.