Add Widget Text

Recommended sequence:

1. widget.tree.inspect to find the current WidgetTree.
2. widget.palette to find TextBlock or another widget class.
3. schema.inspect for widget.tree.edit operation addFromPalette.
4. widget.tree.edit to add the widget under the chosen parent.
5. widget.inspect for the widget instance before setting properties.
6. widget.tree.edit to set widget or slot properties.
7. widget.compile.

Use WidgetTree tools for hierarchy changes. Use inspect results to choose property names and slot property paths.