Piwik 2.16.1, Chrome 51 under Windows 8.1.
PHP 5.5.x , Apache 2.4.x
After letting a tab open over a period of time > 20 minutes, some red graphics disappear when switching to Piwik's tab like in this screenshot:
Just switching to another tab and then coming back to Piwik "solves" the problem. uBlocl origin is set to "off" on my Piwik site.
This is not critical but I was curious if I was alone with this behavior...
I updated my Chrome to 53 and didn't get the misbehavior in the last 5 hours... I'll close the ticket tomorrow if it doesn't happen again.