Edited Issue: Transparent Background in RichTextBox [20547]

When setting Colors.Transparent as FontBackgroundColor the Background changes to Colors.White.
So instead of setting Color.Transparent in ApplyPropertyValueToSelectedText the background should be cleared.

My current workaround in RichTextBoxFormatBar looks like this

```
void ApplyPropertyValueToSelectedText(DependencyProperty formattingProperty, object value)
{
if ((value == null) || (Target == null) || (Target.Selection == null))
return;
if (value is SolidColorBrush && (value as SolidColorBrush).Color == Colors.Transparent)
{
Target.Selection.ApplyPropertyValue(formattingProperty, null);
}
else
{
Target.Selection.ApplyPropertyValue(formattingProperty, value);
}
}
```
Comments: ** Comment from web user: BoucherS **

This issue will be fixed in v2.3