onPointerCaptureAcquired
Confirms that this node acquired one captured gesture on the owning tree thread.
The consumed press callback has returned, the runtime has installed its capture reference, and no captured drag, move, release, or cancellation has run yet. A consumed press does not imply acquisition when another node already owns capture, so implementations that retain gesture state should begin it here. The default implementation retains no state. If this callback fails, terminal tree cleanup clears ownership before invoking onPointerCaptureCancelled.
Parameters
button
the button whose consumed press acquired capture.
Throws
when gesture initialization fails; the tree preserves that failure while cancelling the installed capture during cleanup.