Code review comment for lp:~fboucault/messaging-app/async_bottom_edge

This is not working correctly in 2 column mode, compared to shipping version. Found two issues, testing as follows:

Hardware: Arale
Changed the grid units to make arale go into 2 column mode when rotate:
create this file: /etc/ubuntu-touch-session.d/arale.conf with contents
GRID_UNIT_PX=14

Tests:
1) rotate phone into landscape, causes 2 column mode
Expected results: no bottom edge hint in column 1, only + button on toolbar to create new page
Actual result: bottom edge hint displayed in column 1, invoking it brings up empty page

2) rotate phone into landscape, causes 2 column mode
-- select an existing conversation, verify thread view is open
-- press the + button from header
Expected results: thread view in column 2 is fully replaced with New Message view, "New Message" entry added to top of column 1
Actual results: thread view is not replaced (or partially replaced) in column 2, no "New Message" entry added to column 1