GTK - Adding touch event with an image display

[venkat <venkat s vortexindia co in>]

I have an GTK image that to be displayed in the screen which has some 
menu list as shown below.

*http://i.stack.imgur.com/ZVkMV.gif*

All these days for the image reference we will be having some reference 
keys near the displayed menu,where users generally click on the 
respective keys and select an option.
Now.We are migrating to touch screen where i need to create a touch event.

One possible solution is I can have something like invisible buttons and 
get the touch event.But. what is the general way of handling these 
conditions

Please guide