Page Whiteouts after opening Firefox Screenshots while holding the Escape button

[emilghittasv]

[Affected versions]:
Firefox 54.0b6 (Build Id:20170508210007)
Firefox Screenshots 6.6.0

[Affected platforms]:
Windows 10 64 bit
MacOS 10.10.5
Ubuntu 16.04 64bit

[Steps to reproduce]:

1. Open Firefox with a clean profile.
2. Enable Firefox Screenshots.
3. Access the https://reddit.com website.
4. Hold the keyboard’s Escape button.
5. Click the Firefox Screenshots button.

[Expected result]:
Firefox Screenshots does not open.

[Actual result]:
The entire page whiteouts.

[Additional notes]
Please note that you may have to repeat step 5 (while holding the Escape button) a couple of times to reproduce this issue.
Please observe the following video for more information: https://drive.google.com/open?id=0B94iuIVMr-TEWm13NmxjZWh5aFk

[johngruen]

Yeah, not sure exactly what's happening here, but it's gross. we should probably just disable screenshots if the user is depressing the esc key. I can repro this, but it seems to be maybe the result of a race condition b/c it doesn't happen every time, and seems to arbitrarily through push notification errors.

[johngruen]

Actually after doing this i'm getting constant error notifications every 5-10 seconds. Closing the original tab seems to resolve.

[ianb]

I'm not getting quite the same errors, but I am seeing problems where the iframe isn't initialized in this case. It's easy to imagine it could then produce regular errors. I don't see any error that causes the iframe not to be initialized, the errors all come later.

My best first guess is that holding Escape causes something to try to tear down during initialization.

[ckprice]

Moving to stretch + may go away when we change button handler code.