Why would you change the main content width? The main content shouldn’t be accessible when the sidemenu is open.
If you want two contents to stay both on the same page (like the iPad Settings app), you should use the ui-router
It makes sense for specific use cases, like an email app, where navigating quickly through a list (side nav) to see the content (emails), while in landscape mode, would necessitate resizing and showing the content in its entirety.
I think dynamically resizing the content is a simpler and more efficient option than duplicating it
I know what you mean, I don’t think the Ionic sideMenu should be used to build a side scrollable list (which needs to be always on the left and not only when the user opens the sideMenu).
In the link I gave you in the previous post there’s a simple tutorial on how to create multiple views (eg. in a email app you need a view for the scrollable list of mails on the left and another view for the mails’ contents).