Это пример. Поместите событие GotFocus и LostFocus в текстовое поле (на странице .xaml).
<TextBox x:Name="UrlTextBox" Text="Search" Margin="0,0,98,0" GotFocus="UrlTextBox_GotFocus" LostFocus="UrlTextBox_LostFocus"/>
На странице xaml.cs добавьте следующие коды-
private void UrlTextBox_GotFocus(object sender, RoutedEventArgs e)
{
if (UrlTextBox.Text == "Search")
{
UrlTextBox.Text = "";
SolidColorBrush Brush1 = new SolidColorBrush();
Brush1.Color = Colors.Gray;
UrlTextBox.Foreground = Brush1;
}
else
{
char[] strDataAsChars = UrlTextBox.Text.ToCharArray();
int i = 0;
for (i = UrlTextBox.SelectionStart - 1; ((i >= 0) &&
(strDataAsChars[i] != ' ')); --i) ;
int selBegin = i + 1;
for (i = UrlTextBox.SelectionStart; ((i < strDataAsChars.Length) &&
(strDataAsChars[i] != ' ')); ++i) ;
int selEnd = i;
UrlTextBox.Select(selBegin, selEnd - selBegin);
}
}
private void UrlTextBox_LostFocus(object sender, RoutedEventArgs e)
{
if (UrlTextBox.Text == String.Empty)
{
UrlTextBox.Text = "Search";
SolidColorBrush Brush2 = new SolidColorBrush();
Brush2.Color = Colors.Gray;
UrlTextBox.Foreground = Brush2;
}
}