Integrate Thickbox jquery plugin into your blogs. Open Images and Native Galleries on the same window without touching the html code.
This plugin allows to use the thickbox features for images and wordpress galleries without touching the html. It includes an option "Open in the same window" on the edit panel before inserting the image on your post.
For the native wordpress galleries the plugin inserts the "thickbox" class name and rel properties automatically.
You can also edit the html if you want to use Thickbox in any other links.
Visit the plugin page for more details.