This is Microsoft Windows functionality and it can be adjusted in machine's Performance settings.
Enable Previewing of Thumbnails in Windows Explorer:
- Right–click Computer;
- Select Properties;
- Click Advanced System Settings;
- Under Performance section click Settings;
- Tick the check–box near Show thumbnails instead of icons;
- Click Apply; and
- Click OK twice.
Please note that CGM preview will only work if Cortona 2D Viewer corresponds to Operating System type. This article explains how to know your System type.