UDM 4 is valid XHTML, and in our judgement, meets the criteria for WAI Triple-A conformance.
The most significant potential conflict is with malformed HTML - the navigation structure is vulnerable to coding errors earlier on the page. If you have any layout or configuration problems, the first thing to do is validate the page it's on. Opera has a useful feature for this - you can validate local pages from the document context menu.
Other than that, the only HTML conflicts you're likely to encounter are with windowed controls, iframes or Flash movies.
Windowed controls are objects which are rendered by the
OS, rather than by the browser;
some have a z-order of infinity,
so if another element is positioned above it, the object will
show through. The most
common example of this is the <select> element in
Windows Internet Explorer 5 and 6.
Thankfully, for
Win/IE5.5-6
this problem is a thing of the past.
Using a trick known as the
Iframe shim it's possible to have
DHTML layers
above <select> elements, without them showing through.
This technique is so robust that
the menus can go above any embedded content,
even Java applets or media players!
(The <iframe> is hidden
with opacity so that you can still have transparent content in the menus.
Opacity is rendered using Direct X, which in Internet Explorer is
an ActiveX control (at the same security level as plugins like Flash),
so for anyone who has Active-X disabled completely
the <iframe> will have a white background).
This trick doesn't work for
Win/IE 5.0,
so the script also includes a conventional hiding routine that makes
<select> elements invisible when the menus are open.
This routine, and the iframe shim,
are controllable with the
manage windowed controls for win/ie variable.
No other
supported browsers have a problem with <select> elements,
but some may have problems with iframes or Flash movies:
Opera 7 and 8, Konqueror 3, Mac/IE5
and Win/IE5.0
cannot place menus above an <iframe>.
There is no workaround, and auto-hiding iframes would look disturbing;
so I suggest you try to design around the co-incidence of
menus and iframes, as far as possible.
In Win/IE5.5-6, Flash movies are not an issue because of the trick used to keep menus above windowed controls. But for other browsers there's a couple of extra steps you can take, which should allow the menus to go above Flash:
z-index; the z-index should be
lower than the
navbar's base z order.
<param name="wmode" value="transparent" />
within an <object>, or the
wmode attribute of
<embed> - wmode="transparent".
Some users have reported that this only works in Firefox
if the wmode parameter has the value
"opaque". There's a test page for these
parameters at
communitymx.com.
For further documentation please visit the Macromedia Flash Support Center.
UDM 4 is valid XHTML, and in our judgement, meets the criteria for WAI Triple-A conformance.
