How to get the coordinates of a TPaveText?

is there a way to get the coordinates of a TPaveText. In the documentation, I found the methods GetX1NDC, GetY1NDC, GetX2NDC and GetY2NDC
However I do not understand at all what they return.
I attached a small routine which shows the “problem”.
I define a TPaveText with the position 0.5,0.5,0.6,0.6. and when I asked to show what are the X/Y1/2NDC values, I got very strange values.
Typically, running the routine gives me
1.2624e-316 1.35221e-312 1.2624e-316 1.26239e-316

Basically, I would just move a TPaveText to another position.
Do I something wrong?
test.C (203 Bytes)

// ... pt->Draw(); gPad->Modified(); gPad->Update(); // make sure it's really drawn // ...

That’s it.
Thank you
A bit troublesome this need to call the Modified and Update methods…