Change to SPLIT-TWO-TABBED layout (made first container hold two windows).

i3-layout-manager/layouts/layout-SPLIT-TWO-TABBED.json

@@ -4,7 +4,7 @@
 		"floating": "auto_off",
 		"fullscreen_mode": 0,
 		"layout": "splith",
-		"percent": 1,
+		"percent": null,
 		"type": "con",
 		"nodes": [
 		{
@@ -24,7 +24,27 @@
 					"x": 0,
 					"y": 0
 				},
-				"percent": null,
+				"name": "",
+				"percent": 0.5,
+				"swallows": [
+				{
+					"instance": ""
+				}
+				],
+				"type": "con"
+			},
+			{
+				"border": "pixel",
+				"current_border_width": 5,
+				"floating": "auto_off",
+				"geometry": {
+					"height": 450,
+					"width": 651,
+					"x": 0,
+					"y": 0
+				},
+				"name": "",
+				"percent": 0.5,
 				"swallows": [
 				{
 					"instance": ""
@@ -51,7 +71,27 @@
 					"x": 0,
 					"y": 0
 				},
-				"percent": null,
+				"name": "",
+				"percent": 0.5,
+				"swallows": [
+				{
+					"instance": ""
+				}
+				],
+				"type": "con"
+			},
+			{
+				"border": "pixel",
+				"current_border_width": 5,
+				"floating": "auto_off",
+				"geometry": {
+					"height": 450,
+					"width": 651,
+					"x": 0,
+					"y": 0
+				},
+				"name": "",
+				"percent": 0.5,
 				"swallows": [
 				{
 					"instance": ""