Viber desktop additional feature integration for

Hi I want to add extra features to viber desktop, these features are choose more than one contact to message, and choose all contacts. I think the requirements are quite clear. I am attaching a copy of the program in case you are not familiar with it. This is the desk top window version and the work is required on this version. Please carefully read the requirements and only qualified freelancer should bid, don't waste your time and mine.