The window host's place() is asynchronous — it opens the window, waits for
/pane to load, and only then adopts the element in. But the manager emits
`panes:opened` as soon as place() returns, and the chip reacts by putting its
"popped out" stub where the element used to be.
So for that gap the user saw BOTH: the real panel still sitting in its
original spot, and a stub next to it claiming the panel had left. On a window
that never loads, that lasts the full 10s readiness timeout.
Detach the element as soon as we commit to moving it. That is not destructive:
the node keeps its owner document, its listeners and its closures — it is
simply out of the tree, waiting for a document to be adopted into. And if the
window never loads, closePane() puts it straight back at its home, which is
exactly what the failure path already does.
The dock host has no such gap; its place() moves the element synchronously.
Signed-off-by: topkoa <topkoa@gmail.com>
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