Never use UIA for Mozilla Gecko. (#17694)
Summary of the issue:
Firefox (and thus other applications based on it or Gecko) now has a native UI Automation implementation. It is not yet enabled by default. However, once it is (likely in a few months), NVDA will use it automatically. This is definitely undesirable because NVDA doesn't support browse mode for Firefox with UIA. Even if it did, IA2 is still more suitable for web content in most screen readers.
Description of user facing changes
Mozilla Firefox will work with NVDA the same as it always has, even once Firefox enables native UI Automation support.
Description of development approach
Added the window classes used by Gecko to UIAHandler.badUIAWindowClassNames.
