Added a dynamic layout system where UI elements can be moved about on a tiled grid.

scripts/layout_edit_overlay.gd

@@ -0,0 +1,19 @@
+@tool
+extends Control
+
+var selected_rect := Rect2()
+var candidate_rect := Rect2()
+var show_candidate := false
+var candidate_valid := true
+
+func _draw() -> void:
+	if not $Actions.visible:
+		return
+	var accent := get_theme_color("accent", "SurfaceSide")
+	draw_rect(selected_rect.grow(-1), accent, false, 2)
+	if show_candidate:
+		var ink := accent if candidate_valid else get_theme_color("fault", "SurfaceSide")
+		var fill := ink
+		fill.a = 0.12
+		draw_rect(candidate_rect.abs(), fill)
+		draw_rect(candidate_rect.abs(), ink, false, 3)