How to create a custom 'tree picker' view for a reference type dictionary field.Issue Customers often have a business requirement to either customize an existing tree-picker dialog [or] create a new tree-picker for a custom field.ResolutionCreate custom tree picker for a reference type field In order to customize a tree-picker for any dictionary field, we need to create a new UI (user interface) page and write custom HTML, Client script, Processing script according to our business requirement. This UI page can also include "UI Scripts" and can be included in the HTML section of the page.Refer the OOB (out of box) UI (user interface) Page: kb_categories_dialog for more information on custom UI page creation.The custom UI page has to be used in a UI Macro by using 'GlideDialogWindow' [or] 'GlideDialog' in the XML (extensible markup language)Refer the OOB UI Macro: kb_category_reference_lookup for more information on custom UI Macro creation and calling a UI Page within a macro.Choose the 'Reference' field on which you need to show the tree picker view and open the sys_dictionary record of the reference field.Go to the 'Attributes' related list and add the dictionary attribute Field decorations and the value for this attribute should be the name of the UI Macro created in step 4.Refer to the image below. Example Open any kb_knowledge record and click on the reference lookup icon for 'Category' field.Observe that the categories are shown in a tree structure in a dialog box.The config files involved are:UI Script:/sys_ui_script.do?sys_id=906bad13d731210013ab49547e61039cUI Page: /sys_ui_page.do?sys_id=1160fcb1d731210013ab49547e610376UI Macro: /sys_ui_macro.do?sys_id=0622c2dcd7a21200535000285e610300Dictionary entry: 'kb_category' field on kb_knowledge table.