When you move the mouse cursor beyond the data plotting region, the cursor turns into a ruler. This indicates that you are pointing at that axis' attributes. When you left click you can enter a dialog to manually enter that axis' range and the nature of the plot. For example, for real data, if you move the mouse to the bottom of the screen and left click, you can enter a dialog to change the horizontal quantity plotted. This lets you make parametric plots.
For complex data, you can choose to plot either phase, group delay, or nothing against the right vertical axis. You can change the representation of complex data from Bode to Nyquist or Cartesian by moving the mouse to the left vertical axis of complex data.