Panel in syntax 2.0 does not render when current doc has 1.0 syntax

Here is the test case:

1) create a new panel, having XWiki syntax 2.0
2) put this panel in the current layout
3) display a xwiki 1.0 document

The panel does not render, its raw content is displayed instead
The panel is properly rendered when an XWiki 2.0 document is displayed

As far as we had been able to look at this problem without debugging (with the help of Thomas), we were unable to find any obvious cause. Rendering seems to be produced from the textarea displayView function, and, as expected, should normaly takes care of the syntax of the originating document of the object from which the field is displayed.