If the Footprint Expert resizes when you roll the mousewheel as the cursor hovers over the part Viewer window, follow these steps to resolve this issue.

Right click the "Footprint Expert" exe file in your installation directory and click "Properties".
   

Select the Compatibility tab and click "Change high DPI settings".
   

Click the check box to "Override high DPI scaling behavior", then click OK to accept the change and OK again to apply it.