I would like to make a plug-in that adds a widget. I would like it to be based on the current pages widget but add the ability to select either include OR exclude by drop down or checkbox then list pages by ID.
Following this guide I was able to change the exclude to include by hacking the core file located in wp-includes/default_widgets.php.
Here is the original code:
How do I make the changes and turn it into a plugin?