Most of the issues in the previous reply dialog related to the fact
that:
1) The background content was taller than the viewport.
2) Background scrolling is possible with the dialog open.
This change addresses this issue by hiding the bulk of change view
content when any change view dialog is opened, and then re-displaying
it when the dialog is closed, and letting the dialog take up the entire
screen on smaller devices.
Bug: Issue 7080, Issue 7070
Change-Id: I5834fc61e8daeee2972e8dca4fad9ac54bf9ebca
180eb16707