Chrome tab seems to lose layers when left open

[arjunrajlab]

I have found that if you open a tab on nimbusimage.org and then move to another tab of nimbusimage.org, then go back to it after some time, it seems to "lose the layers". It displayed correctly initially, but then looks like this:

After a page refresh, it is fine:

Here is another example of a "lost layer":

If I refresh page, it is fine:

Then I go back to the first tab, and now the annotations are not showing:

Update: If I just have a single tab open, I don't see this behavior. It seems to happen if I open another tab on nimbusimage.org, even if that second tab is on a completely different dataset.

[arjunrajlab]

Update: in talking with @bruyeret seems that we are running out of WebGL contexts. That is probably a fundamental limitation, but perhaps we can show a sign to the user if this happens, saying "Display resources exhausted, refresh page. To avoid in future, trying working in just a single tab at a time."