2D Picking

It all depends how complex your menu is, If it''s a few simple buttons, then when the mouse is pressed simply check if the coordinates are in the rectangles of one of the buttons.

If it''s more complex, you might want to develop a button class that is responsible for reacting to mouse input and checking it''s own boundaries againt mouse actions.

Its not that complex so i go on the mouse coords then

You might want to check out this thread.

It was originally about image swapping, but the gist of the thread is about finding out if a mouse is over a button.