Watermark / hint text / placeholder TextBox

Question

How can I put some text into a TextBox which is removed automatically when user types something in it?

Answer 1

This technique uses the Background property to show / hide placeholder textbox.
Placeholder is shown event when Textbox has the focus

How it works:

• When empty, TextBox background set to Transparent to show PlaceHolder text.
• When not empty background set to White to cover up PlaceHolder text.

Here is basic example. For my own purposes I turned this into a UserControl.

Here is the ValueConverter to detect non-empty strings in the DataTrigger.

public class NotEmptyConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        var s = value as string;
        return string.IsNullOrEmpty(s);
    }
    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        return null;
    }
}