The problem is that Apple Park, its worldwide HQ in Cupertino, California, has been designed in such a way that it's difficult to tell where walls end and doors begin.

The four storey building, designed by Norman Foster, was once described by deceased CEO as the best office building in the world. American news sources said that Apple's real estate vice president admitted there was a problem in January.

Apple has now been forced to put red stickers so that people know where the doors end and the walls begin after employees on their own initiative used post-it notes so they wouldn't bump into the glass.

Some people put stickers on their own windows to prevent birds from flying into them and damaging themselves.

We've heard that some people have problems breaking through glass ceilings, but breaking through doors and walls is a new one on us.

[Picture courtesy of Justin Ormont, licensed under Creative Commons]