How to create a label that moves along with the mouse cursor?

[Chris Dams mi infn it]

Dear all,

I am new to GTK but already succeeded into drawing a graph with real
values on the plane that are color encoded (i.e., in mathematical
language: a function RxR -> R, where RxR is represented by a DrawingArea
and the outcome of the function by a colored pixel at the right position.)
Now I would like to also display the value at the point where the mouse
cursor happens to be inside the drawing area and I would like to do this
by displaying a label next to the mouse cursor on which the value at the
cursor position is shown. It should move along with the cursor and adjust
the value shown depending on the current cursor position. I figured out
that I can respond to pointer motion events and read their co-ordinates,
but I do not know how to create the label to show the appropriate value.
Could someone on this list tell me? Is this possible in GTK?

Many thanks,
Chris