ConstA member answers its placement on the canvas, so the members are laid out in canvas pixels in one box whose transform takes the canvas back into the frame: it undoes the frame's turn and mirror about the frame's center. While the group itself is in a gesture, the same transform maps the committed frame onto the gesture's, so the members follow it before it commits (a plain stretch, without the quadrant rule, until the drop). A member's box carries its id, so a press on it reaches the member (Excel's two-step), and a member's own gesture draws its preview here. Nothing here is a hit target but what the members paint.
Content that holds movables, in the sheet: a container that draws each member with the renderer of its own kind, where the member says it is drawn.