If you want the pop up to stay popped up until your visitor clicks it shut then you need to create a new layer in the Page & Layer Gallery.
Link the trigger object on the mouse off layer to the pop-up layer. There are two options. Close Pop=up Automatically closes the pop-up layer as soon as the visitor clicks off the image. Un-checked, the visitor has to click an X to close the pop-up.
The pop-up layer can be as big or small as you want it to be.
Bookmarks