Patch for TB 68

I made a hacked version (notes below) you can find at:
http://www.tnrglobal.com/2020/05/thunderbird-addons/
Hack issues:
1) It does require TB restart although it doesn't report that.
2) I've mainly used search and Ctl-Shift FIELD for searching,
SO please try your favorite options and let me know if it works.
3) I don't have access to add better update info
4) FYI, This is a legacy mode extension

I call it hacked because I not a extension pro, even if I am a Kernel level professional programmer.
good luck. It is not in any way compromised as many use hacked to mean.
If I get github access I will make a branch for this.

fixes #80

bootstrap.js

@@ -14,11 +14,14 @@ function loadIntoWindow(window) {
   if ( !window ) return; // windows is the global host context
   let document = window.document; // XULDocument
   let type = document.documentElement.getAttribute('windowtype'); // documentElement maybe 'messengerWindow' / 'addressbookWindow'
+
   if ( targetWindows.indexOf(type) < 0 ) return;
+
+  Services.console.logStringMessage("Expression Search: loading ExpressionSearchChrome");
   ExpressionSearchChrome.init(); // will and add my filter, and TB want the domID exists when filter registered, so only called when have window ready
   ExpressionSearchChrome.Load(window);
 }
- 
+
 var windowListener = {
   onOpenWindow: function(aWindow) {
     let onLoadWindow = function() {
@@ -53,15 +56,15 @@ function startup(aData, aReason) {
   // validator warnings on the below line, ignore it
   if ( !sss.sheetRegistered(userCSS, sss.USER_SHEET) ) sss.loadAndRegisterSheet(userCSS, sss.USER_SHEET); // will be unregister when shutdown
 }
- 
+
 function shutdown(aData, aReason) {
   // When the application is shutting down we normally don't have to clean up any UI changes made
-  if (aReason == APP_SHUTDOWN) return;
+  //** if (aReason == APP_SHUTDOWN) return;
 
   try {
     if ( sss.sheetRegistered(userCSS, sss.USER_SHEET) ) sss.unregisterSheet(userCSS, sss.USER_SHEET);
   } catch (err) {Cu.reportError(err);}
-  
+
   try {
     Services.obs.removeObserver(windowListener, observeEvent);
     // Unload from any existing windows