<Button Name="btnOK"
Grid.Column="2"
HorizontalAlignment="Left"
VerticalAlignment="Center"
Command="{Binding Path=OKCommand}"
Content="{DynamicResource Common_Button_OK}"
IsDefault="True"
Style="{DynamicResource ButtonStyle}">
<Button.IsEnabled>
<MultiBinding Converter="{StaticResource InvalidMultiValidationRuleToBooleanMultiConverter}"
ConverterParameter="objectnull|greaterthanzerointeger|greaterthanzerointeger|greaterthanzerointeger">
<Binding ElementName="comboBoxFilter"
Mode="OneWay"
Path="SelectedItem" />
<Binding ElementName="textBoxFrameRate"
Mode="OneWay"
Path="Text" />
<Binding ElementName="textBoxSizeWidth"
Mode="OneWay"
Path="Text" />
<Binding ElementName="textBoxSizeHeight"
Mode="OneWay"
Path="Text" />
</MultiBinding>
</Button.IsEnabled>
</Button>

public class InvalidMultiValidationRuleToBooleanMultiConverter : IMultiValueConverter
{
#region IMultiValueConverter Members

public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
string[] paramlist = ((string)parameter).Split('|');
if (paramlist == null || paramlist.Length <= 0)
{
throw new ArgumentNullException("parameter");
}
int length = paramlist.Length;

IList<bool> boollist = new List<bool>();

for (int i = 0; i < paramlist.Length; i++)
{
switch (paramlist[i].ToLowerInvariant())
{
case "checknameexisted":
boollist.Add(ValidationRuleHelper.Validate<InvalidCheckNameExistedValidationRule>(values[i]));
break;
case "directoryandfileexist":
boollist.Add(ValidationRuleHelper.Validate<InvalidDirectoryAndFileExistValidationRule>(values[i]));
break;
case "greaterthanzerointeger":
boollist.Add(ValidationRuleHelper.Validate<InvalidGreaterThanZeroIntegerValidationRule>(values[i]));
break;
case "numericnull":
boollist.Add(ValidationRuleHelper.Validate<InvalidNumericNullValidationRule>(values[i]));
break;
case "stringlength":
boollist.Add(ValidationRuleHelper.Validate<InvalidStringLengthValidationRule>(values[i]));
break;
case "stringnullorempty":
boollist.Add(ValidationRuleHelper.Validate<InvalidStringNullOrEmptyValidationRule>(values[i]));
break;
case "ipaddress":
boollist.Add(ValidationRuleHelper.Validate<InvalidIPAddressValidationRule>(values[i]));
break;
case "objectnull":
default:
boollist.Add(ValidationRuleHelper.Validate<InvalidObjectNullValidationRule>(values[i]));
break;
}
}

bool result = boollist[0];
for (int i = 1; i < boollist.Count; i++)
{
result = result & boollist[i];
}

return result;
}

public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
{
return null;
}

#endregion
}