Binding erros appears when clicking on the Operator/Constants option in the left tree:

System.Windows.Data Error: 40 : BindingExpression path error: 'Children' property not found on 'object' ''ConstantEditorItemModel' (HashCode=24850331)'. BindingExpression:Path=Children; DataItem='ConstantEditorItemModel' (HashCode=24850331); target element is 'RadTreeViewItem' (Name=''); target property is 'ItemsSource' (type 'IEnumerable')

System.Windows.Data Error: 40 : BindingExpression path error: 'Children' property not found on 'object' ''OperatorEditorItemModel' (HashCode=64577580)'. BindingExpression:Path=Children; DataItem='OperatorEditorItemModel' (HashCode=64577580); target element is 'RadTreeViewItem' (Name=''); target property is 'ItemsSource' (type 'IEnumerable')

Currently, the RadExpressionEditor control shows a wavy underline and a red color to indicate that an error is present.

We could introduce API to modify this behavior, which will ultimately be used by the ChangeUnderlineDecoration and ChangeUnderlinesColor methods of the internal RadRichTextBox control.

Allow the string representation of editors to be customized e.g. change the NotEqual operator from "<>" to "!=".

Respect DisplayNameAttribute of the added fields from fields list in ExpressionTextBox.

When creating an expression that has a decimal, if it doesn't have a zero in front of the decimal, it doesn't evaluate the expression:
eg:  0.02 is valid , .02 is invalid