Use this to paint a group or a panel object by passing the object variable and an RGBA color ([x,x,x,x])

paintPanelGroupScriptUI.jsx

function FillPanel(panelOBJ, color) {
	if (
		panelOBJ &&
		color &&
		(panelOBJ.type == "panel" ||
			panelOBJ.type == "group" ||
			panelOBJ.type == "dialog" ||
			panelOBJ.type == "palette" ||
			panelOBJ.type == "window") &&
		panelOBJ.graphics.BrushType
	) {
		try {
			color[3] = color[3] == undefined ? 1 : color[3];
			if (!(color.length >= 3)) {
		// color is not propper rgb array
				return;
			}

			var g = panelOBJ.graphics;

			if (g !== undefined) {
				g.backgroundColor = g.newBrush(g.BrushType.SOLID_COLOR, color);
			}
		} catch (e) {
			// something went wrong, you could print or alet an error here
		}
	}
}