setOnCopyFromMenu method
Sets the callback to be invoked when the Copy menu item is selected.
The callback should return a Future that completes with true if the
operation was handled, or false to allow the default system behavior.
Parameters:
callback: The callback to invoke, ornullto clear the handler.
Implementation
@override
void setOnCopyFromMenu(Future<bool> Function()? callback) {
_onCopy = callback;
}