Highlight selected ship lab cards

IconButton.gd

@@ -35,6 +35,10 @@ const REFERENCE_SIZE: float = 56.0
 
 @export var icon: int = Icon.MAP
 @export var glow_color: Color = Color(0.25, 0.85, 1.0)
+# Selection is an additional frame, never a recolour. It lets menus retain
+# semantic colours (vessel class, danger, cargo) while still making the
+# active choice unmistakable.
+@export var highlighted: bool = false: set = set_highlighted
 # Colour of the bright core stroke. Defaults to near-white, which reads well
 # on the dark space background; scenes drawing over a bright backdrop (the
 # lunar surface) override this with a dark colour so the button doesn't wash
@@ -56,6 +60,13 @@ func set_enabled(value: bool) -> void:
 	queue_redraw()
 
 
+func set_highlighted(value: bool) -> void:
+	if highlighted == value:
+		return
+	highlighted = value
+	queue_redraw()
+
+
 func _ready() -> void:
 	queue_redraw()
 
@@ -126,6 +137,16 @@ func _draw() -> void:
 		Vector2(margin, rect_size.y - margin),
 	])
 	NeonDraw.draw_glowing_polygon(self, square, _active_color(), pulse, core_color)
+	if highlighted:
+		# The inset frame reads as a selection focus ring. It deliberately uses
+		# the bright core rather than the button's glow colour, so selecting a
+		# blue shield or pink transporter does not change what that colour means.
+		var inset: float = 10.0 * s
+		var focus: PackedVector2Array = PackedVector2Array([
+			Vector2(inset, inset), Vector2(rect_size.x - inset, inset),
+			Vector2(rect_size.x - inset, rect_size.y - inset), Vector2(inset, rect_size.y - inset),
+		])
+		NeonDraw.draw_glowing_polygon(self, focus, core_color, 1.0, core_color, 0.72 * s)
 
 	var center: Vector2 = rect_size / 2.0
 	match icon: