pub(crate) fn selector_default_pos(ctx: &Context) -> Pos2Expand description
Where the selector window opens when no position was carried over — the first build of a session.
The window’s bottom-right corner sits one overlay margin from the screen’s, so the list opens out of the way of the frame-rate readout and the fullscreen button in the top corners. The window is seeded by its bottom-right pivot, so that corner stays put as the content decides the window’s size; a window a user has dragged is carried by its whole rectangle, which a rebuild restores exactly.