For those whose eyes might glaze over when reading that blog post, can you give an example of a key sequence that produces the desired character or comment command in Internet Explorer but not in Firefox?

Example of a sequence is OEM_7 + OEM_7 + o producing ő (you have to have the layout from the example, I'm not sure if there is a standard layout containing chained deadkeys). Also note that it works in Explorer (like Start Menu or searching on Windows) rather than in Internet Explorer.

I have found an installer of a layout containing chained dead keys: http://www.kbdedit.com/manual/examples/KbdEditInstallerUSChainedDeadKeyMultiAccent.exe

You can produce ő by sequence (ACUTE, ACUTE, o), where ACUTE is AltGr+OEM_7.

I think it will be hard to get clear answers about custom keyboard layouts here...

I did see a bug that sounds related: 791300 – Dead-key diacritics non-functional in text forms and address bar -- the last comment mentions a code comment that chaining is not supported.

About the bug tracking system:

• Bugzilla Etiquette
• Voting

See also http://mxr.mozilla.org/mozilla-release/source/widget/windows/KeyboardLayout.cpp