I have found a related question here:
Automatically set the 'number' option in Vim when entering Ex mode, set 'nonumber' in visual mode
Still I am not sure that I can follow those explanations to achieve what I want.
So here is what I want to achieve:
For normal (and visual) mode, I've set up a color bar, for example here I [ab]use the foldcolumn to indicate that I am in visual mode (see on the left a blue vertical bar):
Now if I go into insert mode I want it to change the color (now the bar is gray as if it is gone):
I want this to set up a strong visual feedback which helps
to always see in which mode I am currently.
Sometimes I start to input text when I am in normal or visual mode and this results in running a lot of Vim's commands.
So how can I make that the color changes automatically in run-time when switching from insert to normal mode and back?
Here I use is foldcolumn, but it can be something else with similar effect to this.
VIM 7.4, Windows