pop up menu right clicking on a tree item

[Giovanni Masullo <Giovanni Masullo icn siemens it>]

can anyone tell me how i can capture the mouse
right click on a tree item?
i would like to do that to putting up a popup menu
related to that item.
PS
maybe these questions i'm making are trivial, but
"have mercy on me!" i'm a beginner with gtk.

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