You can easily add content inside a container, such as a panel, in the native HTML canvas. However, if the Autosize Children property is enabled, the container moves when you try to add content to it. To prevent this movement, use the following steps:

1. Click to select and freeze the container to which you want to add content.
2. On the Components tab, in the Generic Elements group, choose an object, such as a text box, that you want to add to the container.
3. Click in the container again to add the element. For example, draw the text box and type the text.
4. Click the element to select it.

   In the Properties panel, under Autosize options, click Accept any changes, if you want the element to resize automatically.

   Click Keep size and position, if you want the element to remain fixed in the container.

5. Right-click the canvas and click Update Layout.

   The content now appears inside the container.