AFAIK the best you can do for store ones (short of asking for mounting to be disabled which isn't 100% reliable) is set the mount distance as high as it goes in the settings.
Hi, Snowlz, You can also write a plugin that will prevent mounting. It will need to snag the OnMountUp event, and arrange to cancel it. A plugin that does this may already exist. If so, a forum search should help you find it. cheers, chinajade