The availability of the Filter Editor is controlled by the DataViewBase.AllowFilterEditor option. By default, this property is set to true, allowing end-users to use the Filter Editor. End-users can invoke the Filter Editor using the 
button, which is displayed within the Filter Panel or via the Column Header Context Menu.
In code, the Filter Editor can be opened via the DataViewBase.ShowFilterEditor method. To customize the Fillter Editor before it is displayed, handle the DataViewBase.FilterEditorCreated event.
The Filter Editor's UI can be localized. For details on localizing DevExpress WPF products, see Localization.
The Filter Editor displays filter criteria as a tree structure, where nodes represent simple filter conditions. If the filter criteria consist of multiple filter conditions, the Filter Editor contains multiple nodes linked by logical operators into groups. For instance, the following image shows the Filter Editor representing the "[Product] = 'Chang' And [Quantity] > 20" filter expression:
Conditions combined by a logical operator at the same level form a group. You can think of groups as clauses wrapped by round brackets in the filter expression. There is only one group in the example above. In the following example, the filter expression contains two groups combined by the logical OR operator. The expression "([Product] = 'Chang' And [Quantity] > 20) Or ([Product] In ('Tofu', 'Konbu') And [Quantity] < 100)" is represented in the Filter Editor as follows:
The image below shows the Filter Editor, indicating its UI elements.
