Vertical layout partially works

backends/x/entity.go

@@ -34,8 +34,10 @@ func (ent *entity) unlink () {
 		delete(ent.window.system.drawingInvalid, child)
 		return true
 	})
-	
-	delete(ent.window.system.drawingInvalid, ent)
+
+	if ent.window != nil {
+		delete(ent.window.system.drawingInvalid, ent)
+	}
 	ent.parent = nil
 	ent.window = nil
 }

backends/x/system.go

@@ -98,7 +98,7 @@ func (system *system) afterEvent () {
 }
 
 func (system *system) layout (entity *entity, force bool) {
-	if entity == nil { return }
+	if entity == nil || !entity.isContainer { return }
 	if entity.layoutInvalid == true || force {
 		entity.element.(tomo.Container).Layout()
 		entity.layoutInvalid = false