diff --git a/internal/system/box.go b/internal/system/box.go
index f08ebb0..57a74b5 100644
--- a/internal/system/box.go
+++ b/internal/system/box.go
@@ -19,6 +19,8 @@ type box struct {
 	parent parent
 	outer  anyBox
 
+	role tomo.Role
+
 	bounds              image.Rectangle
 	minSize             image.Point
 	userMinSize         image.Point
@@ -106,6 +108,10 @@ func (this *box) MinimumSize () image.Point {
 	return this.minSize
 }
 
+func (this *box) Role () tomo.Role {
+	return this.role
+}
+
 func (this *box) borderSum () tomo.Inset {
 	sum := tomo.Inset { }
 	for _, border := range this.border {
@@ -182,6 +188,10 @@ func (this *box) SetPadding (padding tomo.Inset) {
 	this.invalidateMinimum()
 }
 
+func (this *box) SetRole (role tomo.Role) {
+	this.role = role
+}
+
 func (this *box) SetDNDData (dat data.Data) {
 	this.dndData = dat
 }