fix for #8219. only honor delete of a news message (cancel) when from the menu.

mailnews/base/resources/content/messenger.xul

@@ -301,7 +301,7 @@ Rights Reserved.
       <menuitem name="&cutCmd.label;" onclick="MsgEditCut();"/>
       <menuitem name="&copyCmd.label;" onclick="MsgEditCopy();"/>
       <menuitem name="&pasteCmd.label;" onclick="MsgEditPaste();"/>
-      <menuitem name="&deleteMsgCmd.label;" onclick="MsgDeleteMessage();"/>
+      <menuitem name="&deleteMsgCmd.label;" onclick="MsgDeleteMessage(false);"/>
       <menuitem name="&deleteFolderCmd.label;" onclick="MsgDeleteFolder();"/>
       <menu name="&selectMenu.label;">
       <menuitem name="&selectAllCmd.label;" onclick="MsgSelectAll();"/>
@@ -510,7 +510,7 @@ Rights Reserved.
 	  <titledbutton src="&newMsgButton.img;" align="bottom" value="&newMsgButton.label;" onclick="MsgNewMessage()"/>
 	  <titledbutton src="&replyButton.img;" align="bottom" value="&replyButton.label;" onclick="MsgReplyMessage()"/>
 	  <titledbutton src="&forwardButton.img;" align="bottom" value="&forwardButton.label;" onclick="MsgForwardMessage()"/>
-	  <titledbutton src="&deleteButton.img;" align="bottom" value="&deleteButton.label;" onclick="MsgDeleteMessage()"/>
+	  <titledbutton src="&deleteButton.img;" align="bottom" value="&deleteButton.label;" onclick="MsgDeleteMessage(true)"/>
 
           <spring flex="100%"/>
 	  <titledbutton src="&throbber.img;" align="right" onclick="MsgHome('&throbber.url;')"/>

mailnews/base/resources/content/widgetglue.js

@@ -56,17 +56,29 @@ function MsgGetMessage()
   GetNewMessages();
 }
 
-function MsgDeleteMessage()
+function MsgDeleteMessage(fromToolbar)
 {
   dump("\nMsgDeleteMessage from XUL\n");
+  //dump("from toolbar? " + fromToolbar + "\n");
+
   var tree = GetThreadTree();
   if(tree) {
-    dump("tree is valid\n");
-	//get the selected elements
-    var messageList = tree.getElementsByAttribute("selected", "true");
-	//get the current folder
 	var srcFolder = GetThreadTreeFolder();
-    messenger.DeleteMessages(tree, srcFolder, messageList);
+	// if from the toolbar, return right away if this is a news message
+	// only allow cancel from the menu:  "Edit | Cancel / Delete Message"
+	if (fromToolbar) {
+		uri = srcFolder.getAttribute('id');
+		//dump("uri[0:6]=" + uri.substring(0,6) + "\n");
+		if (uri.substring(0,6) == "news:/") {
+			//dump("delete ignored!\n");
+			return;
+		}
+	}
+	dump("tree is valid\n");
+	//get the selected elements
+	var messageList = tree.getElementsByAttribute("selected", "true");
+	//get the current folder
+	messenger.DeleteMessages(tree, srcFolder, messageList);
   }
 }