I want to develop an application for "ubuntu app showdown". Can i use Closed Source Application for artworks or icons ? like Corel or Photoshop or etc. (What if i use them with winehq in ubuntu?)
Yes as long as the icons you create are your own work. If you create new images you are the copyright holder and can do with them as you please. In this context photoshop or corel are legally no different from a pen and paper - adobe own the rights to photoshop's code, but not the rights to everything produced with it (if they did people would soon stop using it!).