Annoying beep, flashes on using vim

Vim :help visualbell comes up with:

‘visualbell’ ‘vb’

Use visual bell instead of beeping. The terminal code to display the visual bell is given with ‘t_vb’. When no beep or flash is wanted, use “:set vb t_vb=”. Note: When the GUI starts, ‘t_vb’ is reset to its default value. You might want to set it again in your |gvimrc|. In the GUI, ‘t_vb’ defaults to “<Esc>|f”, which inverts the display for 20 msec. If you want to use a different time, use “<Esc>|40f”, where 40 is the time in msec.

Aha! Now I know from where I was getting those annoying visual flashes(for 20msec) when I was working on GNU screen over vpn which was apparently slow.

I searched and searched for how to disable this visual flash while editing source code with vim. But in vain.

Now I know: set vb t_vb=