gdk-window-device-position (window device)

window -- a gdk-window object
device -- a gdk-device object to query

win -- the gdk-window object underneath device, as with the gdk-device-window-at-position function, or nil if the window is not known to GDK
x -- an integer with the x coordinate of the device
y -- an integer with the y coordinate of the device
mask -- the gdk-modifier-type flags

Obtains the current device position and modifier state. The position is given in coordinates relative to the upper left corner of window. Use the gdk-window-device-position-double function if you need subpixel precision.