A Boolean property that sets the allowTransparent attribute of the IFRAME that makes up the panel. This is an Internet Explorer (7 and under) only attribute which, when true, allows the document loaded in the panel to have a transparent background-color.
It is important to note that this property does not make the panel transparent, it simply allows the panel contents to be transparent. The content document must still set its BODY background-color to transparent. If this property is false then any transparent background-color in the content document will be ignored.
This is a non-standard property that is only supported by Internet Explorer (7 and under) or Internet Explorer 8+ running in compatability mode. Other browsers (including Internet Explorer 8+ running in standards mode) do not support this property. They will behave as if transparent is true. However, if no background color is specified in the content document, some browsers will default to transparent and other browsers will default to white. So, for best cross-browser results, leave this property as true and make sure you explicitly set the background color of your content document.
true() or false()