About Picking Object

I want to make the function that permits to pick the object by mouse, it kind of likes RTS game. But the first thing got me stumped. when I called the function "showCursor" to make the cursor visible, my binding function of the mouse button wouldn't be called. (for instance, the callback function "pickTruck" is binded by calling the command "moveMap.bind(mouse, button0, pickTruck);"). Does anyone know the reason and how to solve it?

Thanks for any help in advance.