Any mouse button will work. You may have to wait for a moment for the button to be depressed. Applications will often have many embedded controls, such as sliders and buttons. The Image application displays a two-dimensional slice of a data set. If the data set dropped into it is three-dimensional, and if that data set is also dropped into a data slider that is linked into Image, the slider will pick which slice gets displayed.
Many applications can control others, sometimes in less than immediately obvious ways.
To find out how to get information from one application to another, either experiment or look up the help file for each application. For example, 2D Scatterplot can control Image in an unusual way. Morphing Some windows disappear and are replaced by another window when such actions are called for. We call this 'morphing'. These displays have and buttons that simply enlarge or shrink the image.