Hiding Ground Texture Temporarily

[tirediron]

I was watching a YouTube video on Trainz, and the presenter seemed to be able to 'turn off' or hide the ground texture effects temporarily to reveal the grid underneath and allow for better alignment of buildings, etc. Unfortunately, he's moving so quickly (and the video isn't actually a 'How to') that I can't quite see what he might be doing to make this happen. Is there a quick-key combination or menu option, of which I'm unaware that has this functionality?

Thanks!

 

[euromodeller]

Press F9 to get the wireframe grid and press it again to return your textures

Cheers
Graham

 

[tirediron]

THANK-YOU!!!!!!!!!!!!!