I tried to use a YUI Rich Text Editor inside a YUI Panel that starts out hidden. However, some of the time, the place that the YUI Editor occupies was covered with a white square, even when the panel was hidden.
This example by Dav Glass provides the solution. IE6 does not properly handle visibility:hidden for iframes. The solution is to position the iframe offscreen when it’s hidden, and restore it when it’s shown again.