> 1) The fist rendering of the homescreen after rebooting the mobile phone we can see the placeholder with an axe for icons like a web page

I noticed that too but I think we see it only when the lockscreen is disabled. Can the user disable it ?

> 2) Moreover, this visibility was used for repainting the new icon after downloading process finishes. Please take a look at http://apptester.eu01.aws.af.cm/ and install "Big hosted app" (@arcturus)

mmm I tried that too and didn't notice anything.

I did this change because I noticed that sometimes the homescreen stays empty for a long time (say 1s) after some actions. I'm not sure this helps but I didn't see it anymore with this patch so..

But I can revert this change and we can handle this separatly if you feel this is better.