Safari and the z-index flash problem

http://www.w3.org/TR/CSS21/visuren.html#z-index

'z-index'

Value: auto | <integer> | inherit

http://www.w3.org/TR/CSS21/syndata.html#numbers

Some value types may have integer values (denoted by <integer>) or real number values (denoted by <number>). Real numbers and integers are specified in decimal notation only. An <integer> consists of one or more digits "0" to "9". A <number> can either be an <integer>, or it can be zero or more digits followed by a dot (.) followed by one or more digits. Both integers and real numbers may be preceded by a "-" or "+" to indicate the sign. -0 is equivalent to 0 and is not a negative number.

Note that many properties that allow an integer or real number as a value actually restrict the value to some range, often to a non-negative value.

So basically there are no limitations for z-index value in the CSS standard, but I guess most browsers limit it to signed 32-bit values (−2147483648 to +2147483647) in practice (64 would be a little off the top, and it doesn't make sense to use anything less than 32 bits these days)

I'm not sure if this will help you per se. But I've used following method to show content over flash.

I had faced this problem some time ago. I was to show user a popup for Terms and Conditions for registration on a site. Popup was coming okay, but There was a flash movie at top of the page which was hidding upper portion of the dialog. The tested and widely used method is to put an Iframe at place where you want to show your content and absolute position your content and IFrame. For example, if you want to show a div above a flash movie, then place a IFrame like follows:

    <iframe style="position:absolute;top:250;left:150;"></iframe>

Then position the div exactly above this iframe like:

    <div style="position:absolute;top:250;left:150;"></div>

I was using jquery on the page to show dialog using ui.dialog plugin. After fooling around sometime I devised following simple solution.

1) put id attribute on movie element to uniquely identify the movie object. Like,

<object id="movie1"></object>

2) before showing the dialog (or other content for that matter) call a javascript function to hide the movie. Like,

$("#movie1").css("display","none");

3) now show dialog. Like,

$("#dialog").dialog("open");

4) after closing the dialog, show the movie again. Like,

  $("#dialog").dialog("close");
  $("#movie1").css("display","inline");