I haven't looked real closely but based on this the function b30a50 is for ondrag not onclick?
Code:
.text:013CB7AF push offset aUi_shop_ondrag ; "UI_Shop_OnDrag"
.text:013CB7B4 mov dword_16A42A8, eax
.text:013CB7B9 mov dword_16A42AC, offset sub_B30A50
.text:013CB7C3 mov dword_16A42B0, offset aUi_shop_ondrag ; "UI_Shop_OnDrag"
B30A80 looks like the click handler?
Code:
.text:013CB7D2 push offset aUi_shop_onclic ; "UI_Shop_OnClick"
.text:013CB7D7 mov dword_16A42B4, eax
.text:013CB7DC mov dword_16A42B8, offset sub_B30A80
.text:013CB7E6 mov dword_16A42BC, offset aUi_shop_onclic ; "UI_Shop_OnClick"
I could be wrong this is just a simple quick look through ida for you
I haven't actually tested this