Display accounts in the account manager even if the associated protocol plugin cannot be found.

im/base/content/instantbird/account.js

@@ -46,7 +46,7 @@ var account = {
     this.account = window.arguments[0];
     this.proto = this.account.protocol;
     document.getElementById("accountName").value = this.account.name;
-    document.getElementById("protocolName").value = this.proto.name;
+    document.getElementById("protocolName").value = this.proto.name || this.proto.id;
     document.getElementById("protocolIcon").src =
       this.proto.iconBaseURI + "icon48.png"
 
@@ -206,6 +206,8 @@ var account = {
         throw "unknown preference type " + opt.type;
       }
     }
+    if (!gbox.firstChild)
+      document.getElementById("advancedTab").hidden = true;
   },
 
   getValue: function account_getValue(aId) {

im/base/content/instantbird/account.xml

@@ -238,7 +238,15 @@
         var bundle = document.getElementById("accountsBundle");
         const key = "account.connection.error";
         var account = this._account;
-        var text = account.connectionErrorMessage;
+        var text;
+        if (account.connectionErrorReason == Ci.purpleIAccount.ERROR_UNKNOWN_PRPL) {
+          document.getAnonymousElementByAttribute(this, "anonid", "connect")
+                  .setAttribute("disabled", "true");
+          text = bundle.getFormattedString(key + "UnknownPrpl",
+                                           [account.protocol.id]);
+        }
+        else
+          text = account.connectionErrorMessage;
         text = bundle.getFormattedString(key, [text]);
 
         this.setAttribute("error", "true");

im/locales/en-US/chrome/instantbird/accounts.properties

@@ -2,6 +2,7 @@
 protoOptions=%S Options
 
 account.connection.error=Error: %S
+account.connection.errorUnknownPrpl= No '%S' protocol plugin.
 account.connection.progress=Connecting: %S...
 account.connecting=Connecting...
 account.reconnectInDouble=Reconnection in %S %S and %S %S.

im/themes/winstripe/instantbird/jar.mn

@@ -17,6 +17,9 @@ classic.jar:
 	skin/classic/instantbird/prpl-generic/icon32.png	(prpl/prpl-generic-32.png)
 	skin/classic/instantbird/prpl-generic/icon48.png	(prpl/prpl-generic-48.png)
 	skin/classic/instantbird/prpl-generic/icon.png		(prpl/prpl-generic.png)
+	skin/classic/instantbird/prpl-unknown/icon32.png	(prpl/prpl-unknown-32.png)
+	skin/classic/instantbird/prpl-unknown/icon48.png	(prpl/prpl-unknown-48.png)
+	skin/classic/instantbird/prpl-unknown/icon.png		(prpl/prpl-unknown.png)
 % skin prpl-aim classic/1.0 %skin/classic/prpl/aim/
 	skin/classic/prpl/aim/icon32.png	(prpl/prpl-aim-32.png)
 	skin/classic/prpl/aim/icon48.png	(prpl/prpl-aim-48.png)