Screens — overview
The Screens page — left scope bar of apps, flat list of screens, click to open the Screen Designer's 7 tabs (General / Queries / Columns / Dialog / Actions / Row menu / Export).
Create a screen from a query
Wire a `_get` query to a fresh screen — the General tab and the Queries tab walked through field by field; the grid appears, edits land via the write queries.
Columns
The Columns tab — set each column's display title, format, dictionary reference, edit rule, default and filtering once; both the grid and the dialog use them.
Dialog builder
The Visual Builder — a three-column Figma-style canvas (Palette / Canvas / Inspector) where you drag fields onto tabs, set properties, wire lookups and add per-tab actions.
Conditional fields
Make a dialog field appear, be required or be locked only when another field has a specific value — visible_when / required_when / disabled_when on ColumnHint and ScreenField.
Actions and lifecycle
The Actions tab — toolbar buttons, row context menu, dialog hooks (on_load / on_save / on_cancel), row hooks (on_insert / on_update / on_delete), and the seven core action types.
Nested tabs
Embed a child-record form (nested_form) or a related-rows grid (nested_table) in a dialog tab — same dialog, multiple data sources.