• ‘Zoom’: to zoom in/out, namely to increase/decrease the view magnification factor making the displayed objects appear larger/smaller, roll up/down the mouse central wheel. Alternatively, you can zoom in a specific area by drawing a fence with the mouse while keeping the [CTRL] button pressed.
• ‘Fit View’: in order to make the whole set of displayed objects to fit the view, namely to make them occupy as much larger portion of the visible scene as possible, either Select the [Fit View] item from the [View] menu or just press the space bar of the keyboard.