There are 2 ways of doing this.
Mark the ones you don't want to show in the list as module (Solution Settings) and they won't show up in the webclient list AND in the rich client list.
So you can
only open them with Developer then.
If that's not what you want you might want to create a 'portal' solution that shows the modules a user can use and hides the ones it can't.
This way you have 1 single point of entry for all users.
If you want a special property for not showing solutions in webclient but still showing them in rich client then I suggest you file a feature request in the
Servoy bugbase
Hope this helps.