fix bugs

src/vs/workbench/common/editor/editorStacksModel.ts

@@ -308,7 +308,7 @@ export class EditorGroup implements IEditorGroup {
 	private splice(index: number, del: boolean, editor?: EditorInput): void {
 
 		// Perform on editors array
-		const args:any[] = [index, del];
+		const args:any[] = [index, del ? 1 : 0];
 		if (editor) {
 			args.push(editor);
 		}
@@ -319,14 +319,20 @@ export class EditorGroup implements IEditorGroup {
 			this.mru.push(editor);
 		}
 
-		// Remove: remove from MRU
-		else if (del && !editor) {
-			this.mru.splice(this.indexOf(this.editors[index]), 1);
-		}
-
-		// Replace: replace MRU at location
+		// Remove / Replace
 		else {
-			this.mru.splice(this.indexOf(this.editors[index]), 1, editor);
+			const editorToDeleteOrReplace = this.editors[index];
+			const indexInMRU = this.indexOf(editorToDeleteOrReplace, this.mru);
+
+			// Remove: remove from MRU
+			if (del && !editor) {
+				this.mru.splice(indexInMRU, 1);
+			}
+
+			// Replace: replace MRU at location
+			else {
+				this.mru.splice(indexInMRU, 1, editor);
+			}
 		}
 	}
 
@@ -411,7 +417,7 @@ export class EditorStacksModel implements IEditorStacksModel {
 
 		// Subsequent group (add to the right of active)
 		else {
-			this._groups.splice(this.indexOf(this.active), 0, group);
+			this._groups.splice(this.indexOf(this.active) + 1, 0, group);
 		}
 
 		// Event

src/vs/workbench/test/common/editorStacksModel.test.ts

@@ -83,34 +83,40 @@ suite('Editor Stacks Model', () => {
 		assert.equal(model.groups.length, 0);
 		assert.ok(!model.activeGroup);
 
-		const first = model.openGroup('group');
+		const first = model.openGroup('first');
 		assert.equal(events.opened[0], first);
 		assert.equal(events.activated[0], first);
 		assert.equal(model.activeGroup, first);
 		assert.equal(model.groups.length, 1);
+		assert.equal(model.groups[0], first);
 
 		const second = model.openGroup('second');
 		assert.equal(events.opened[1], second);
 		assert.equal(events.activated[1], second);
 		assert.equal(model.activeGroup, second);
 		assert.equal(model.groups.length, 2);
+		assert.equal(model.groups[1], second);
 
 		const third = model.openGroup('third');
 		assert.equal(events.opened[2], third);
 		assert.equal(events.activated[2], third);
 		assert.equal(model.activeGroup, third);
 		assert.equal(model.groups.length, 3);
+		assert.equal(model.groups[2], third);
 
 		model.closeGroup(first);
 		assert.equal(events.closed[0], first);
 		assert.equal(model.groups.length, 2);
 		assert.equal(model.activeGroup, third);
+		assert.equal(model.groups[0], second);
+		assert.equal(model.groups[1], third);
 
 		model.closeGroup(third);
 		assert.equal(events.closed[1], third);
 		assert.equal(events.activated[3], second);
 		assert.equal(model.activeGroup, second);
 		assert.equal(model.groups.length, 1);
+		assert.equal(model.groups[0], second);
 
 		const fourth = model.openGroup('fourth');
 		assert.equal(fourth, model.activeGroup);