@EvilSOB:
You reckon that your code will never execute the "my.z += 10;" part?
The problem is this section:
Code:
space_pressed = 1;
if(space_pressed==0)   player.z += 10;

First you set space_pressed to 1 and then check if its 0. But at that point it'll never be 0 because you set it to 1 first.

Try replacing the whole jumping part with:
Code:
if(key_space} 
{
  space_pressed = 1;
}
else
{
  if(space_pressed)
  {
    space_pressed = 0;
    my.z += 10;
  }
}