Sets Python code evaluated when the UI is drawn.
`L` is the layout object; use Blender's layout API to build the UI.
This code also runs on redraw. Place buttons for actions such as adding or removing objects,
rather than performing those actions directly while drawing.

```python
# Display a label inside a box
L.box().label(text="Add Mesh")
```

```python
# Arrange several buttons vertically
col = L.column(); col.operator("mesh.primitive_cube_add", text="Cube"); col.operator("mesh.primitive_uv_sphere_add", text="Sphere")
```

These are two independent examples. To place several UI elements in one Pie Menu slot,
wrap them in a single column or box as in the second example.
Adding multiple elements directly to the pie layout can shift subsequent slots to different directions.

The input limit is **1,024 UTF-8 bytes**.
See [Code Input and Execution](/reference/command_text.md) for
length limits, multiline code, and external scripts.