selectionControls property
Optional delegate for building the text selection handles.
Historically, this field also controlled the toolbar. This is now handled
by contextMenuBuilder instead. However, for backwards compatibility, when
selectionControls is set to an object that does not mix in
TextSelectionHandleControls, contextMenuBuilder is ignored and the
TextSelectionControls.buildToolbar method is used instead.
Implementation
final TextSelectionControls? selectionControls;