Expression editor
Since version 9.0
NOTE
For details on the expression language please see Expressions.

Code items
The code items side-bar allows you to quickly build the expression. Double the click the required method/field and it will be added to the window at the cursor, or overwrite a selection.
NOTE
Parameters will be added like variable and need to be replaced with your own arguments.
Intellisense
Only basis intellisense is available at the moment. However the code items window allows you to browse properties of various classes.