gdk:window-set-shadow-width (window left right top bottom)

window -- a gdk:window object
left -- an integer with the left extent
right -- an integer with the right extent
top -- an integer with the top extent
bottom -- an integer with the bottom extent

Newer GTK windows using client-side decorations use extra geometry around their frames for effects like shadows and invisible borders. Window managers that want to maximize windows or snap to edges need to know where the extents of the actual frame lie, so that users do not feel like windows are snapping against random invisible edges.

Note that this property is automatically updated by GTK, so this function should only be used by applications which do not use GTK to create toplevel windows.