looking for an invisible button

[fabien derreal <fabien derreal enst fr>]

Hi all

I'm designing a small programm with a skinned keyboard.
I have nice pixmaps for each key one when normal and one when hit.
All I need is to put them in an invisible container mouse-sensitive (
press, released, clicked).

To have them sensitive, I put them in buttons.
it's the only container sensitive to the mouse I've found so far.
Even  with

    gtk_button_set_relief((GtkButton*) pbutton[i],GTK_RELIEF_NONE);
    gtk_container_set_border_width((GtkContainer*) pbutton[i],0);

I get a small border for the "active button" (the one my mouse is over).

Does anyone know

    - if there is another GTK container which would best fit my needs.
or - if there are other options to get my buttons more invisible
or - if i should write my own widget?

thanx a lot