You can now choose which GeoCheckpoints (found, placed, unfound) you want to display on the map. There are three checkboxes below the map. By default, all of them are checked. If you don't want to display some group of GeoCheckpoints (e. g. hidden by you), simply uncheck the checkbox.
This feature was created as a bonus feature for supporters. However, you can still get the supporter package for free so everybody can enjoy this new functionality. Check out the "Become Supporter" link in the members control panel to get the free supporter package.
Note: If the new feature does not work for you it may be necessary to clear browser cache (using CTRL + F5).
Thanks to geocite for suggesting this feature!