Handles a drop event.

def dropEvent( self, event ):
        """
        Handles a drop event.
        """
        url  = event.mimeData().urls()[0]
        url_path = nativestring(url.toString())
        
        # download an icon from the web
        if ( not url_path.startswith('file:') ):
            filename = os.path.basename(url_path)
            temp_path = os.path.join(nativestring(QDir.tempPath()), filename)
            
            try:
                urllib.urlretrieve(url_path, temp_path)
            except IOError:
                return
            
            self.setFilepath(temp_path)
        else:
            self.setFilepath(url_path.replace('file://', ''))