forgot to push for a while, got drag-and-drop mostly working

RowGrid.cs

@@ -0,0 +1,61 @@
+using Godot;
+using System;
+
+public partial class RowGrid : PanelContainer
+{
+	protected Vector2 _CardSize;
+	public Vector2 CardSize
+	{
+		get => CardSize;
+		set
+		{
+			_CardSize = value;
+			UpdateCardSize();
+		}
+	}
+	protected Color _RowColor;
+	public Color RowColor
+	{
+		get => _RowColor;
+		set
+		{
+			_RowColor = value;
+			UpdateRowColor();
+		}
+	}
+	protected void UpdateCardSize()
+	{
+		foreach (var c in this.GetAllDescendents<card>())
+			c.CustomMinimumSize = _CardSize;
+	}
+	public const float RowBackgroundColorScale = 2;
+	private static Color ScaleColor(Color color)
+	{
+		return new Color
+		{
+			R = 1 - (1 - color.R) / RowBackgroundColorScale,
+			G = 1 - (1 - color.G) / RowBackgroundColorScale,
+			B = 1 - (1 - color.B) / RowBackgroundColorScale,
+			A = color.A,
+		};
+	}
+	protected void UpdateRowColor()
+	{
+		var sbf = GetThemeStylebox("panel").Duplicate() as StyleBoxFlat;
+		sbf.BgColor = ScaleColor(_RowColor);
+		AddThemeStyleboxOverride("panel", sbf);
+		sbf = GetNode<Panel>("%RowTitleBoxBackground").GetThemeStylebox("panel").Duplicate() as StyleBoxFlat;
+		sbf.BgColor = _RowColor;
+		GetNode<Panel>("%RowTitleBoxBackground").AddThemeStyleboxOverride("panel", sbf);
+	}
+	// Called when the node enters the scene tree for the first time.
+	public override void _Ready()
+	{
+
+	}
+
+	// Called every frame. 'delta' is the elapsed time since the previous frame.
+	public override void _Process(double delta)
+	{
+	}
+}