Implemented window margins for Grids and Stacks.

grid.go

@@ -139,8 +139,11 @@ func (g *Grid) allocate(x int, y int, width int, height int, d *sysSizeData) (al
 	ymargin := d.ymargin
 	d.xmargin = 0
 	d.ymargin = 0
-_=xmargin
+	// 0) inset the available rect by the margins
-_=ymargin
+	x += xmargin
+	y += ymargin
+	width -= xmargin * 2
+	height -= ymargin * 2
 	// 1) clear data structures
 	for i := range g.rowheights {
 		g.rowheights[i] = 0

stack.go

@@ -89,8 +89,11 @@ func (s *Stack) allocate(x int, y int, width int, height int, d *sysSizeData) (a
 	ymargin := d.ymargin
 	d.xmargin = 0
 	d.ymargin = 0
-_=xmargin
+	// 0) inset the available rect by the margins
-_=ymargin
+	x += xmargin
+	y += ymargin
+	width -= xmargin * 2
+	height -= ymargin * 2
 	// 1) get height and width of non-stretchy controls; figure out how much space is alloted to stretchy controls
 	stretchywid = width
 	stretchyht = height

test/main.go

@@ -41,6 +41,7 @@ func gridWindow() *Window {
 		l20, c21, l22)
 	g.SetFilling(1, 2)
 	g.SetStretchy(1, 1)
+	w.SetSpaced(*spacingTest)
 	w.Open(g)
 	return w
 }