The old policy was to invoke magit in fullscreen, but in practice, I've
found myself wanting to peek at other buffers (maybe even notes) while I
manage my project in version control.
So this change introduces two big changes and one fix:
+ Instead of a full-frame policy, we use full-column. e.g. Invoking
magit-status will take up a full column of windows (and will restore
them when you quit).
+ Popups are displayed below the current window if called from a magit
buffer, otherwise as a popup at the bottom of the frame.
+ Fixes popups opening in a random window if called from a magit buffer
in a popup.
This is only a start and needs more testing.
2cc5d223fe