formulas or scripts for periodic savings

[adrian15]

Hello this is my first message to the list.

I've been using for 3 weeks gnucash with the double account mode in order 
to control my personal money.

I have only a bank account but however I can't control my spents with only 
one account. 
To control my spents I supose I have 4 accounts in my bank:

Normal account: Normal spents and earnings.
Entertainment account: Music, Video, Going out the night, buying electronic 
things, linux magazines.
Inversion account: Money spent in things that are quite worth but not 
things as cars or so on.
Patrimony account: Cars, loans and savings.

My laws are the following: 
============================
You cannot expend more than 10% that you earn in entertainment.
You cannot expend more than 20% that you earn in inversion.
When you finish the months if you have won something save it to your 
patrimony.

So what happens every end of the month (28/29/30/31) ?
It happens that I sum all of earnings of the month (usually from my work).

Let's suppose the result is 400 E.

And then samba begins:

40 E goes from Normal account to Entertainment account.
80 E goes from Normal account to Inversion account.

Now I sum all of expenses of the month (included money that goes to 
Entern... and to Inver...) (Ex: 220 E) and I make:

Benefits = Earnings - expenses of the month = 400 - 220 = 180

So samba continues:

180 E goes from Normal account to Patrimony account.

================

Having three virtual accounts for your different expenses gives me many 
problems but I'm going to expose you only one of the problems.

I want to automatise the last 180 E. That's it. I want to schedule a 
function that puts (Earnings of the month - Expenses of the month) from 
Normal account to Patrimony account.

===============

I've looked around the gnu online documentation and I haven't found 
anything about scripts or functions in Gnucash... so is there any way of 
doing what I'm looking for? Any work-around?

Any help is apreciated.

adrian15