Quick select item

[hgdplaygame]

I want to add funtion quick select item by hold key Shift and use mouse. I don't know where to add a code or active this funtion. I need help

 

[xxradicaldxx]

You will have to add this function in the code.
Where?
InterfaceLib

 

[hgdplaygame]

You will have to add this function in the code.
Where?
InterfaceLib

Thanks you, I will read that file. I left C++ about 8 years and have forgotten most of it. I hope i can understand