PROBLEM FIXED I changed the keyboard layout to English and then i could do it. However, it should probably be possible with another layout.

this is a mac, no page-up/down and the problem is that when i press + it decrease and no other key (i think) increase size. Someone?

I am running mac with a Swedish keyboard. By mistake i pressed the "+" button on my keyboard and the screen/viewport went very small. I am now unable to scale the screen back to max size, as a matter of fact i am not able to scale it back to any other size. I did logon to a Windows system with Swedish keyboard and there it worked. I also noticed that it was the "+" key that decreased the size. Nothing happens when i press the "-" key. Can someone please advice me how to fix this problem?