Yes! noticed loads of floating comments etc. I do find them a little irritating.

They don't go away if I scroll, I have to leave the page or click on each box and there are often three of them Hmmm!

@amoun
I knew I had seen sites where the bootstrap alert box fades away after some time. Success!
Added the javascript below to Collection >> Settings >> Advanced >> Custom javascript after body

<script type="text/javascript">
<!--

$(document).ready(function () {

window.setTimeout(function() {
    $(".alert").fadeTo(1500, 0).slideUp(500, function(){
        $(this).remove(); 
    });
}, 5000);

});
//-->
</script>

Found here
http://www.queryadmin.com/997/automatically-close-twitter-bootstrap-alert-message/

Tested here
http://permasteader.com/b2e7/index.php/minisite/instant-pot-ribs

Just leave a comment, submit and wait 5 seconds - they fade away. Probably could be a little faster but of course that depends on how long the warning message is. Need to give people time to read it.
There's a few different methods discussed here
https://stackoverflow.com/questions/23101966/bootstrap-alert-auto-close
One about half way down the page by ADTC looks similar but I haven't tried it because the above seems to work. Then there's one further down that has 10 votes that is almost identical. (minus two forward slashes, two dashes and a greater than symbol or right arrow)

Couldn't find auto close/dismiss thing on getbootstrap. This page does give examples of dismissing but not automatically after a certain time. All require a click.

Won't help us with this forum unless we can get @fplanque to implement it but we can use it on our sites. I also noticed here on the forum that some alerts are inline(or in between elements), some as the top layer and some below everything else and you can see the shadow of them on the left and catch a glimpse of them in between other page elements when you scroll up/down. The green and blue alerts are the ones that hide underneath stuff.

Disclaimer: I know nothing about javascript so I don't know if the above snippet might be security issue. Everything but the time limit can be seen on getbootstrap site though, so it's probably alright.

Just tried out that one that's almost identical and it works too.

<script type="text/javascript">

$(document).ready(function () {

window.setTimeout(function() {
    $(".alert").fadeTo(1000, 0).slideUp(1000, function(){
        $(this).remove(); 
    });
}, 5000);

});
</script>

http://permasteader.com/b2e7/index.php/a/welcome-to-your-b2evolution-powered

And another, shorter version, that works. Shorter snippet and also shorter time limit - 2000 milliseconds. This one has setTimeout while the previous ones have window.setTimeout Have no idea what the difference is but obviously there's more than one way to close a bs alert with javascript

<script type="text/javascript">
$(document).ready(function() {
    // show the alert
    setTimeout(function() {
        $(".alert").alert('close');
    }, 2000);
});
</script>

https://permasteader.com/b2e/index.php/recipe/instant-pot-ribs
This one's b2evo v6. The previous ones were b2evo v7 alpha
Kinda like this last one just because it's less code but I might add window. to it
I did test these on forum too and it works as well.
https://permasteader.com/b2e/index.php/forums/bs-alert-test-for-new (shorter/last version but with .window added)

Thanks will add something like that and get back here to confirm.

Reworking the alert Message sis on the todo list but not the "urgent" list.

I don't want to auto fade important messages. I want to have less non-important messages that are floating.

Or instead of fading, they should actually just slide back to the top of the page.

On the stackexchange page there's some js for slide up. Some say it didn't work for them, some say it worked fine.
On getboostrap, they show how to add the word "Dismiss" to the alert box which makes it a little easier to close than hitting the tiny X. Especially for us old guys.

btw, Post #5, bs alert = BootStrap alert

@poorboy2 wrote earlier:

btw, Post #5, bs alert = BootStrap alert

Good you clarified that, definitely thought you were so fed up with taurus manure that you abbreviated. Still I think the s word it what I thought and think when it happens, like the popup on new install that just won't flush and hangs around uninvited.

Not something I made up either. Bootstrap calls their own stuff BS