How to abolish "SPECIFIC PRICE" while VOUCHER is entered?

[tazosmr]

hello.

for X product, i have specific 30% discount.

i want, that when i use voucher(i.e. 40%), it shouldnt be combined with the "specific price" (so, i want that specific price should be terminated while using voucher).

 

(i have been looking through .php files, and cant fin which one does the job... people were talkin about "cumulate with price deductions" option, but in 1.5 version there is not such option.)

Edited June 14, 2013 by tazosmr (see edit history)