clean up my fix for #75942 to not give a JS error in the filter dialog.

(I forgot the search terms are shared.)  also make it so if you hit enter in
a search term and the search has started, it will stop it and and start a new one.
rename gButton to gSearchStopButton, since that is what it is.
sr=bienvenu

mailnews/base/resources/content/mailWidgets.xml

@@ -400,7 +400,7 @@
     <handlers>
 	<handler event="keypress"><![CDATA[
 	  if (event.keyCode == 13) {
-	    onSearch(); 
+	    onEnterInSearchTerm(); 
           }
         ]]></handler>
     </handlers>

mailnews/base/search/resources/content/FilterEditor.js

@@ -64,6 +64,11 @@ function filterEditorOnLoad()
     moveToAlertPosition();
 }
 
+function onEnterInSearchTerm()
+{
+  // do nothing.  okOk() will get called since this is a dialog
+}
+
 function onOk()
 {
     if (isDuplicateFilterNameExists())

mailnews/base/search/resources/content/SearchDialog.js

@@ -46,7 +46,7 @@ var gNextMessageViewIndexAfterDelete = -1;
 var gDataSourceSearchListener;
 var gViewSearchListener;
 
-var gButton;
+var gSearchStopButton;
 var gSearchSessionFolderListener;
 var gMailSession;
 
@@ -109,7 +109,7 @@ var gSearchNotificationListener =
 
     onSearchDone: function(status)
     {
-        gButton.setAttribute("label", gSearchBundle.getString("labelForSearchButton"));
+        gSearchStopButton.setAttribute("label", gSearchBundle.getString("labelForSearchButton"));
 
         var statusMsg;
         // if there are no hits, it means no matches were found in the search.
@@ -133,7 +133,7 @@ var gSearchNotificationListener =
 
     onNewSearch: function()
     {
-      gButton.setAttribute("label", gSearchBundle.getString("labelForStopButton"));
+      gSearchStopButton.setAttribute("label", gSearchBundle.getString("labelForStopButton"));
 //        if (gThreadTree)
 //            gThreadTree.clearItemSelection();
 
@@ -227,7 +227,7 @@ function initializeSearchWindowWidgets()
 {
     gFolderPicker = document.getElementById("searchableFolders");
 //    gThreadTree = document.getElementById("threadTree");
-    gButton = document.getElementById("search-button");
+    gSearchStopButton = document.getElementById("search-button");
     gStatusBar = document.getElementById('statusbar-icon');
 
     msgWindow = Components.classes[msgWindowContractID].createInstance(nsIMsgWindow);
@@ -298,6 +298,20 @@ function onChooseFolder(event) {
     }
 }
 
+function onEnterInSearchTerm()
+{
+  // on enter
+  // if not searching, start the search
+  // if searching, stop and then start again
+  if (gSearchStopButton.getAttribute("label") == gSearchBundle.getString("labelForSearchButton")) { 
+     onSearch(); 
+  }
+  else {
+     onSearchStop();
+     onSearch();
+  }
+}
+
 function onSearch()
 {
     // set the view.  do this on every search, to