I don't know if anyone is still looking for an answer to this, but this ended up working me and is based on a method scrounged from Stackoverflow. It checks for the f5 default title and then substitutes the title you want. A document change event handler (MutationObserver) is added to detect any later reversion of the title by the f5 base code. On some fast machines, when the webtop posts back to the f5 a 'flicker' in the title can be seen but I only caught this once myself and it settles back to the value that you want in the end.
In your 'header.inc' file, right below the javascript block that adds the function "setViewport" insert this additional script block:
<script language="javascript">
//change the default F5 page title
if (document.title == "F5 Dynamic Webtop") {
document.title = "My Title";
}
// watch to make sure it doesn't get changed on us again
// select the target node
var target = document.querySelector('title');
// create an observer instance
var observer = new MutationObserver(function(mutations) {
if (document.title == "F5 Dynamic Webtop") {
document.title = "My Title";
}
});
// configuration of the observer:
var config = { subtree: true, characterData: true, childList: true };
// pass in the target node, as well as the observer options
observer.observe(target, config);
</script>