Overlay upload - no notification

When clicking the upload button in "Add overlay", there is no notification about the status of the file, or progress of the upload.

This causes confusion - I uploaded the same file a couple of times, there was no block on the button.

Also there is a lag on the upload, longer than in the previous MINERVA version. Because there was no page block, I tried to upload custom layouts, they appeared only after a couple of minutes. I'm not saying the process should be faster, just let me know that I have to wait.