Check the DC class like
http://docs.wxwidgets.org/trunk/classwx%5Fpaint%5Fd%5Fc.html
there you have full freedom. just select a brush, a color and paint copy, stamp store loaded images, what you like. With an Eventhandler like
EVT_LEFT_UP( widget, callback );
you can intercept clicks or with EVT_MOTION the movement with mouse and in the callback the second parameter is the eventobject from where you get coordinates.
just have a look here:
http://docs.wxwidgets.org/2.8.9/wx%5Fclassref.html#classref
because you need to understand some concepts before you can solve such complex task in Wx. Maybe start with the surrounding Wx::Frame, add an Wx::StatusBar a Wx::Menu, put it into the Wx::MenuBar and connect one Menu as Conetxtmenu (also Wx::Menu poped out on mouse click) and so on. You maybe load a little bitmap into menuitem icon before you manipulate it (as Wx::Image, with Wx::Bitmap you can't do a lot). So take your time and enjoy. :)