Fix Bug 314121 - Crash (not reported) then deleted items will not move to trash

Add a messagebox to signal that we must verify imap account trash.
So now we know what to do.

But don't know why trash folder is empty in some case (I never had it)

FIXED-IN: 4.11
BUG: 314121

kmmainwidget.cpp

@@ -2181,9 +2181,10 @@ void KMMainWidget::slotTrashMessagesCompleted( KMMoveCommand *command )
   {
     BroadcastStatus::instance()->setStatusMsg( i18n( "Messages moved to trash successfully." ) );
   } else {
-    if ( command->result() == KMCommand::Failed )
+    if ( command->result() == KMCommand::Failed ) {
       BroadcastStatus::instance()->setStatusMsg( i18n( "Moving messages to trash failed." ) );
-    else
+      KMessageBox::error(this, i18n("Moving messages to trash failed. Please verify your trash in your IMAP account and retry."), i18n("Moving messages to trash failed"));
+    } else
       BroadcastStatus::instance()->setStatusMsg( i18n( "Moving messages to trash canceled." ) );
   }