Don't see option or setting to allow opening Greenshot blank editor - w/o taking a shot or opening a saved file. Can it be done? Or perhaps a preference for extra items to be shown on tray context?
Currently there is no such option, sorry. But this is something we are having on our list, please have a look at this feature request over here: http://sourceforge.net/p/greenshot/feature-requests/499/
Still need to decide where to put it, as a screenshot tool, creating empty images is probably not a key feature for most users :)
Feel free to follow the ticket above to stay up to date on this.