Add a data table widget with sorting, filtering, and in-place editing

[matt-edmondson]

Adds ImGuiWidgets.DataTable, a table of typed rows that sorts and filters itself, moves an active cell with the keyboard, and edits one cell at a time in place. The table never writes to your rows. Each editable column reports the edit through OnEdit, and you apply it, which is what makes undo straightforward.

What it does

• Typed columns. DataTableColumn<TRow, TValue> reads a value, formats it, compares it, and optionally edits it. Strings, numbers, bool and enums have built-in editors, and any other type supplies an Editor.
• Sorting and filtering. Header clicks cycle ascending, descending, and source order. A filter box under each header matches fuzzily by default, and its right-click menu switches to glob or regex. RowFilter adds a condition of your own.
• Keyboard and editing. Arrows, Page Up and Down, Home, End, Tab, and Shift to extend the selection. F2, Enter, double-click, or typing begins an edit. Enter commits and moves down, and Escape cancels.
• Selection. Click, Ctrl+click and Shift+click select rows as shown. Ctrl+C copies them as tab-separated text. SelectRows, ClearSelection and ActivateCell set the selection from code.
• Context menu. OnContextMenu draws caller-supplied items for the right-clicked cell and the selection.
• Keymap. Commands follow a ktsu.Keybinding keymap when one is passed. DataTableCommands.Register registers them.
• Virtualized. Only the rows on screen are drawn, so tens of thousands of rows cost the same per frame as a screenful.

An edited row stays where it is until you call Refresh(), so it doesn't jump away while someone is working on it.

How it's built

DataTableState<TRow> holds the view, the active cell, the selection, and the one edit session, and makes no ImGui calls, so its rules are unit tests. The renderer draws a frame from it and turns input into its commands. The clipper setup is now shared with VirtualTable through TableClipping, with no change to VirtualTable's behavior.

The key chord matcher moved from ImGui.NodeEditor into ImGui.Widgets so both widgets share it. It gained optional key repeat and an option to ignore Shift, and now maps Tab, which it had silently dropped. The node editor's behavior is otherwise unchanged.

The widgets demo gains a Data Table section with undo and redo through ktsu.UndoRedo. The design and plan are in docs/superpowers/specs/2026-09-29-data-table-design.md and docs/superpowers/plans/2026-09-29-data-table.md.

Things to look at

• ImGui.Widgets now references ktsu.Keybinding, which brings Microsoft.Extensions.DependencyInjection.Abstractions to every consumer, plus System.Text.Json on net8.0 and net9.0.
• ImGui.Widgets grants InternalsVisibleTo to ImGui.NodeEditor and the UI tests, and sets PolyUseEmbeddedAttribute so Polyfill's generated extension methods don't become ambiguous across the two assemblies.
• The Ctrl+C UI test reaches the OS clipboard, because ImGui.App installs no clipboard functions. It saves and restores the clipboard around the test.
• Known follow-ups, not in this PR: mouse-triggered commits still run while rows are drawn, the active cell can stay in a column the user hides, and VirtualTable has its own row height mismatch when RowHeight is set.

Testing

The solution builds with 0 warnings. Widget unit tests 458 passed, widget UI tests 423 passed, node editor tests 266 passed, and widgets demo UI tests 30 passed. The UI tests drive the table headlessly, including sorting, filtering, editing, Tab while editing, typing into a filter, keypad Enter, a keymap, and scrolling the last row fully into view.

🤖 Generated with Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
92.6% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud