is designed to scroll the displayed area of the image in the window if the whole image doesn't fit into the window at the chosen scale. To move the image you should press this button, put the cursor onto the image, press the left button and, keeping it pressed, move the image in the window.
To scroll the image in the Image Window you can also press the spacebar on the keyboard and drag the image with the left mouse button.
Double-clicking on the tool's icon on the Toolbar makes the image fit the Image Window.
Scrolling of displayed area with Hand Tool
is designed to change the image scale.
To zoom in left click on the image. To zoom out left click with Alt on the image. You can use hotkeys to change the image scale.
It is also possible to increase the scale of the selected area. For this purpose press and select a rectangular area on the image. When the rectangular area is selected, the image scale will be changed so that the selected part of the image will fill the whole window.
Double-clicking on the tool's icon on the Toolbar makes the image scale to 100% (actual size).
Increasing scale of the selected area with Zoom Tool