Steps to reproduce:

1. Start MS Edge
2. Go to babbage.com
3. Go to the elements list with nvda+f7
4. Press alt+h to focus headings

Expected behavior:

Headings are shown instandly

Actual behavior:

NVDA freezes entirely

Suggested fix

Use watchdog.cancellableExecute for list refreshing, or something similar to this? At least, NVDA should be able to cancel a request for elements.

System configuration:

NVDA version: next-14051,e102a7e0

Windows version: Windows 10 version 1703 (build 15063.296)

Other questions:

Does the issue still occur after restarting your PC?
yes

Have you tried any other versions of NVDA?
Yes, NVDA from source with my i588 branch (#6131)