Calculate and store widget parent id and position when the interfaces are rendered

This removes the need to calculate widget bounds and parent on demand by
traversing up the widget tree.

runescape-api/src/main/java/net/runelite/rs/api/RSClient.java

@@ -156,6 +156,15 @@ public interface RSClient extends RSGameEngine, Client
 	@Import("widgets")
 	RSWidget[][] getWidgets();
 
+	/**
+	 * Gets an array of widgets that correspond to the passed group ID.
+	 *
+	 * @param groupId the group ID
+	 * @return the widget group
+	 * @see net.runelite.api.widgets.WidgetID
+	 */
+	RSWidget[] getGroup(int groupId);
+
 	@Import("region")
 	@Override
 	RSRegion getRegion();

runescape-api/src/main/java/net/runelite/rs/api/RSWidget.java

@@ -40,6 +40,12 @@ public interface RSWidget extends Widget
 	@Override
 	int getId();
 
+	void setRenderParentId(int parentId);
+
+	void setRenderX(int x);
+
+	void setRenderY(int y);
+
 	@Import("parentId")
 	int getRSParentId();