For closer map inspection, the button opens a small window.

The rectangle shows the part of the map appearing in the large window. Use the left mouse button to move the field, to stretch or to compress. Display in the large window will change accordingly. Compressing a rectangle from the corner simultaneous diminishes both sides.

To zoom part of the map, press the left mouse button and without releasing the mouse, draw a rectangle. When the button is released, this part of the map zooms to fill the window. The displayed map can be changed only when the small General view window is open.