Opening images/scenes
The overview images displayed in the overview window each represent a Dicom file.
Double click an overview image to open it. Overview images
representing a multi-image Dicom file (scene) are indicated by the number of
images in the lower right side of the overview image.

Overview images of Dicom scenes
To open biplane images, make sure that the biplane button in the toolbar is pressed and that you double click one of the biplane files. They are recognized by the double square in the top right of the image and, when you single click/highlight one, the corresponding biplane file is highlighted by a dashed line.
If the biplane files differ in size/dimension, the one you double clicked is the one that sets the window size. The other biplane is resized to the same size.

Biplane images, highlighted
Open stack files by double clicking them, make sure you have pressed the 'Show image stacks' button. See 'Opening stacks' for more info.