Thunderbird 57 starts up but doesn't show its main window so needs to be killed
with Task Manager when quickFilters is enabled. There are many other XUL based
addons that exhibit the same behaviors. See also Thunderbird  Bug

https://bugzilla.mozilla.org/show_bug.cgi?id=1417209

I am working with the helpful guys at maildev (Joerg Knobloch etc.) to get this
resolved.

Created an attachment (id=8339) [details]
3.4 prerelease 6

Here is an experimental version  with quite a few adjustments. Did some rough
smoke testing, at least Thunderbird is not prevented from loading its main
window.

When testing, please proceed with caution and have a look for error messages /
warnings  in error console (CTRL+SHIFT+J)

NOTE: This version is ABSOLUTELY NOT compatible with Postbox. (for..of which is
demanded by the new JS engine in Thunderbird cannot be read by the Postbox
parser error free - I will haveto write plenty of SHIM code to maintain
backwards compatibility with their outdated JavaSCript engine)

Should work fine in Thunderbird 57 and Seamonkey.

fixed in quickFilters 3.4