protected void SetPlaceholder() {
Inlines.Clear();
var placeholder = Placeholder;
if (!string.IsNullOrEmpty(placeholder)) {
var inline = new Run { Text = placeholder };
inline.SetBinding(TextElement.ForegroundProperty, new Binding {
Path = new PropertyPath(nameof(Foreground)),
Source = this,
Converter = this
});
Inlines.Add(inline);
}
}