gdk-window-coords-from-parent (window parent-x parent-y)

window -- a gdk-window child window
parent-x -- a number with the x coordinate in parent's coordinate system
parent-y -- a number with the y coordinate in parent's coordinate system

x -- a :double with the x coordinate in child's coordinate system
y -- a :double with the y coordinate in child's coordinate system

Transforms window coordinates from a parent window to a child window, where the parent window is the normal parent as returned by the function gdk-window-parent for normal windows, and the window's embedder as returned by the function gdk-offscreen-window-embedder for offscreen windows.

For normal windows, calling this function is equivalent to subtracting the return values of the function gdk-window-position from the parent coordinates. For offscreen windows however, which can be arbitrarily transformed, this function calls the "from-embedder" signal to translate the coordinates.

You should always use this function when writing generic code that walks down a window hierarchy.

See also the function gdk-window-coords-to-parent.