GDK Button clicks and exposes

[Adam T <simbacat blueyonder co uk>]

Hi all, I am trying to decipher the inner workings of GDK and its 
backends, and I'm looking for a little help if possible!
My current confusion is when to expose a window after a mouse click, so 
far my understanding is thus...

The user clicks the mouse.
The backend decides that this click is for the child window (where the 
button widget is).
This generates a event of type GDK_BUTTON_PRESS.
The backend then call's the GDK function _gdk_event_button_generate, 
which seems to only be concerned with double an triple clicks.
The button press event then goes onto the gdk event queue and is 
processed somewhere within gdk and gtk :/

My question is... does the processing of a button click within gdk 
generate an expose event, to show the button being depressed, or should 
the backend generate this expose event? Generally, how does the 
depressed button get displayed?

Thanks for any help,

Adam