Modal dialogs snap to invisible window edges
With only a single application window open I can find window snapping in the middle of the desktop:
- Open Terminal
- Click X to close the window
- Drag the modal dialog ("Close this terminal?") around, which drags the Terminal window too.
Notice while the modal dialog is open and the main window greyed-out, you can make the pair of them snap to invisible boundaries. This seems to be the dialog rectangle snapping to the old boundaries of the app window before the drag.
I think this may be related to cloning of the greyed-out window, which is something I am looking at elsewhere.