to go against my original idea i don't much like drop shadows LOL (don't listen to me in the future

)
but it made me think, why from the top left? then i did some research and every single OS has used top left as its standard lighting direction for years back... but why?
during design and drawing courses, we were alwyas taught that lighting should come from the top right of a page (generally) as its the 'most' recognised as 3d by the human eye.
all around town i see fake 3d paintings, all done from the top right.
furthermore the lighting setup for OTTD is coming from the top right direction.
i am wondering if (especially if we do drop shadows) we should change the lighting direction to top right....
i would be interested in seeing (that isn't hard to change your icons is it Joed, are they in vector GFX or photoshop?)
just an idea/ observation/ question.
i just don't know why top left is the standard.
Alltaken