Hi, I Have tried the following code on Linux , but the call breaks. Is it because of the X11Window structure missing or else ? Annick ==== testGetOurWindowLocation "self new testGetOurWindowLocation" | display ourWindow aParent anX anY aWidth aHeight aBorderWidth aDepth | display := X11Display XOpenDisplay: nil. ourWindow := display ourWindow. (Alien lookup: 'XGetGeometry' inLibrary: 'X11') primFFICallResult: nil withArguments: {display. ourWindow. (aParent := Alien new: 4). (anX := Alien new: 4). (anY := Alien new: 4). (aWidth := Alien new: 4). (aHeight := Alien new: 4). (aBorderWidth := Alien new: 4). (aDepth := Alien new: 4)}. (anX unsignedLongAt: 1) inspect