registerFocusController method
Registers a focus controller.
The focusController
represents the focus controller of this control.
Implementation
void registerFocusController(FocusController focusController) {
if (_focusController == focusController) {
return;
}
if (_focusController != null) {
unregisterFocusController(_focusController!);
}
_focusController = focusController;
_focusController!.addListener(_onFocusControllerChanged);
}