add DepthButton

src/Styles.gd

@@ -0,0 +1,26 @@
+extends Node
+
+enum CornerType {
+	SINGLE,
+	LEFT,
+	MIDDLE,
+	RIGHT
+}
+
+var _rounded_styles = {}
+
+func _ready():
+	pass # Replace with function body.
+
+func get_key(name: String, corner_type) -> String:
+	return "%s_%s" % [name, CornerType.keys()[corner_type]]
+
+func get_stylebox_flat(original: StyleBoxFlat, name: String, corner_type) -> StyleBoxFlat:
+	var key = get_key(name, corner_type)
+	if _rounded_styles.has(key):
+		return _rounded_styles[key]
+
+	if original != null:
+		return original.duplicate() as StyleBoxFlat
+
+	return StyleBoxFlat.new()