diff --git a/src/vs/vscode.proposed.d.ts b/src/vs/vscode.proposed.d.ts
index 5837d44b84a..0c815176d6b 100644
--- a/src/vs/vscode.proposed.d.ts
+++ b/src/vs/vscode.proposed.d.ts
@@ -2233,7 +2233,12 @@ declare module 'vscode' {
 		readonly label: string;
 
 		/**
-		 * The position of the tab
+		 * The index of the tab within the column
+		 */
+		readonly index: number;
+
+		/**
+		 * The column which the tab belongs to
 		 */
 		readonly viewColumn: ViewColumn;
 
@@ -2250,6 +2255,13 @@ declare module 'vscode' {
 		 */
 		readonly viewId?: string;
 
+		/**
+		 * All the resources and viewIds represented by a tab
+		 * {@link Tab.resource resource} and {@link Tab.viewId viewId} will
+		 * always be at index 0.
+		 */
+		additionalResourcesAndViewIds?: { resource: Uri, viewId: string }[];
+
 		/**
 		 * Whether or not the tab is currently active
 		 * Dictated by being the selected tab in the active group
diff --git a/src/vs/workbench/api/common/extHostEditorTabs.ts b/src/vs/workbench/api/common/extHostEditorTabs.ts
index e44e5d04fdf..d2c2e2a5554 100644
--- a/src/vs/workbench/api/common/extHostEditorTabs.ts
+++ b/src/vs/workbench/api/common/extHostEditorTabs.ts
@@ -14,6 +14,7 @@ import { ViewColumn } from 'vs/workbench/api/common/extHostTypes';
 export interface IEditorTab {
 	label: string;
 	viewColumn: ViewColumn;
+	index: number;
 	resource?: vscode.Uri;
 	viewId?: string;
 	isActive: boolean;
@@ -58,12 +59,15 @@ export class ExtHostEditorTabs implements IExtHostEditorTabs {
 			return Object.freeze({
 				label: dto.label,
 				viewColumn: typeConverters.ViewColumn.to(dto.viewColumn),
+				index,
 				resource: URI.revive(dto.resource),
 				viewId: dto.editorId,
 				isActive: dto.isActive
 			});
 		});
-		this._tabs = this._tabs.sort((t1, t2) => t1.viewColumn - t2.viewColumn);
+		this._tabs = this._tabs.sort((t1, t2) => {
+			return t1.viewColumn === t2.viewColumn ? t1.index - t2.index : t1.viewColumn - t2.viewColumn;
+		});
 		const oldActiveTab = this._activeTab;
 		this._activeTab = activeIndex === -1 ? undefined : this._tabs[activeIndex];
 		if (this._activeTab !== oldActiveTab) {