synthesized property Null safety

If synthesized is true, this event does not correspond to a native event.

Although most of Flutter's keyboard events are transformed from native events, some events are not based on native events, and are synthesized only to conform Flutter's key event model (as documented in the HardwareKeyboard class in the framework).

For example, some key downs or ups might be lost when the window loses focus. Some platforms provides ways to query whether a key is being held. If the embedder detects an inconsistency between its internal record and the state returned by the system, the embedder will synthesize a corresponding event to synchronize the state without breaking the event model.

As another example, macOS treats CapsLock in a special way by sending down and up events at the down of alterate presses to indicate the direction in which the lock is toggled instead of that the physical key is going. A macOS embedder should normalize the behavior by converting a native down event into a down event followed immediately by a synthesized up event, and the native up event also into a down event followed immediately by a synthesized up event.

Synthesized events do not have a trustworthy timeStamp, and should not be processed as if the key actually went down or up at the time of the callback.

KeyRepeatEvent is never synthesized.