Fully transparent window with non-transparent irregular shape graphics

[oOosys]

How to achieve the effect of a fully transparent window with non-transparent irregular shape graphics shown, so that the final effect is to see only he shape on the screen being able to report mouse entering/leaving it and the mouse position and timestamp of the mouse event like click, double click [, triple click ?] , mouse button pressed/released and how to dynamically resize and move the window, so that occupies for example a 20x20 pixels area in the left/bottom screen corner re-appearing at its default size on mouse pointer hovering over it and minimizing on middle mouse button click again to the bottom left corner (where it is invisible because of the transparency)?