How to capture mouse button event in gtkmm?

[jerry <lvjieyong cis pku edu cn>]

Hi, all
A GtkDrawingArea is attached to a window in my program.
And I want to capture the button postion when I click the drawing area.
So I hooked the signal_button_release_event to a function in the window
class, but it seems not working.

More over, I tried to rewrite the on_button_release_event of that
drawingarea class, but with no luck.

Then who can tell me how to solve my problem please?
Thank you in advance.