Hey ! I don't know if someone know that, hammer has logical for entities, like a hud to view how your entities are working, it's not real time preview, but you can see how are linked your entities.
Result:
[Blocked Image: http://i.imgur.com/y6Qv2nZ.png]
but, how to get that ? Easy !
open regedit, search HKEY_CURRENT_USER/Software/Valve/Hammer/Splitter
Then you have "drawtype0,0" "drawtype0,1" "drawtype1,0" "drawtype1,1"
0,0 is camera view, 0,1 is top, 1,0 is side, 1,1 is front
Then you have 4 views to change, you can change what you want.
For this test, use 1,1
[Blocked Image: http://i.imgur.com/Ymc4QgY.png]
Then you can start hammer, select one map exist, you will see the magic !
[Blocked Image: http://i.imgur.com/lknoP7q.png]
It do not look like this at start, you have to move entities etc.
To get the grid, save your vmf, open it with text editor, search the text "bShowLogicalGrid" change the "0" to "1" and load your map.
It's glitchy, it can go black everytime.
Et voila !
Edit: You can try 11 and 12 disabled on csgo, it's light preview
