about-dialog
accel-group -- complete (except some functions which are probably not very useful)
accel-label
accel-map -- complete (except some functions which are probably not very useful)
accessible -- complete
adjustment -- done throught introspection
alignment -- complete
arrow -- done throught introspection
aspect-frame -- done throught introspection
bin -- complete
box -- complete
button -- complete
button-box -- done throught introspection
calendar -- complete
cell-layout -- complete
check-button -- done throught introspection
check-menu-item -- complete
color-button -- done throught introspection
color-selection -- complete minus palette
color-selection-dialog -- complete
combo-box -- complete (up to gtk version 2.4)
combo-box-entry -- complete
container
dialog -- complete
drawing-area -- done throught introspection
editable -- complete
entry -- complete
entry-completion -- complete
event-box -- done throught introspection
expander -- done throught introspection
file-chooser -- complete
file-chooser-button -- done throught introspection (but the dialog property should be readable)
file-chooser-dialog -- done throught introspection
file-chooser-widget -- done throught introspection
file-filter -- complete
fixed -- complete
frame -- complete
font-button -- done throught introspection
font-selection -- complete
frame -- complete
handle-box -- complete
h-box -- done throught introspection
h-button-box -- done throught introspection
h-paned -- done throught introspection
h-ruler -- done throught introspection
h-scale -- done throught introspection
h-scrollbar -- done throught introspection
h-separator -- done throught introspection
image -- complete
image-menu-item -- complete
im-context
im-context-simple
im-multicontext
item -- complete
label -- complete
layout -- complete
list-store -- complete
menu -- complete
menu-bar -- done throught introspection
menu-item -- complete
menu-shell -- complete
menu-tool-button -- complete
message-dialog -- done (up to gtk version 2.4)
notebook -- complete
paned -- complete
plug
progess-bar -- complete
radio-button -- complete
radio-menu-item -- complete
radio-tool-button -- complete
range -- complete
ruler -- complete
scale -- complete
scrollbar -- done throught introspection
scrolled-window -- complete
separator -- done throught introspection
separator-menu-item -- done throught introspection
separator-tool-item -- done throught introspection
size-group -- complete
socket
spin-button -- complete
statusbar -- complete
stock-item -- complete
table -- complete
tearoff-menu-item -- done throught introspection
text-buffer -- complete but the API may change
text-iter -- complete
text-mark -- complete
text-tag -- complete minus text-attributes
text-tag-table -- complete
text-view -- complete
toggle-button -- done throught introspection
toggle-tool-button -- complete
toolbar -- complete
tool-button -- done 
tool-item -- complete (except initialize-instance)
tooltips -- complete
tree-store -- complete
viewport -- done throught introspection
v-box -- done throught introspection
v-button-box -- done throught introspection
v-paned -- done throught introspection
v-ruler -- done throught introspection
v-scale -- done throught introspection
v-scrollbar -- done throught introspection
v-separator -- done throught introspection
widget -- complete (more or less)
window -- complete
window-group -- complete