diff --git a/src/vs/workbench/browser/parts/editor/editorActions.ts b/src/vs/workbench/browser/parts/editor/editorActions.ts
index 33eb7d50e792f..d199084e616ac 100644
--- a/src/vs/workbench/browser/parts/editor/editorActions.ts
+++ b/src/vs/workbench/browser/parts/editor/editorActions.ts
@@ -1087,7 +1087,6 @@ export class ToggleGroupSizesAction extends Action2 {
 	}
 }
 
-
 export class MaximizeGroupHideSidebarAction extends Action2 {
 
 	constructor() {
diff --git a/src/vs/workbench/browser/parts/editor/editorPart.ts b/src/vs/workbench/browser/parts/editor/editorPart.ts
index 630db73810a5c..7d25c62f7aa83 100644
--- a/src/vs/workbench/browser/parts/editor/editorPart.ts
+++ b/src/vs/workbench/browser/parts/editor/editorPart.ts
@@ -375,7 +375,7 @@ export class EditorPart extends Part implements IEditorPart, IEditorGroupsView {
 		this.gridWidget.resizeView(groupView, size);
 	}
 
-	arrangeGroups(arrangement: GroupsArrangement, target = this.activeGroup): void {
+	arrangeGroups(arrangement: GroupsArrangement, target: IEditorGroupView | GroupIdentifier = this.activeGroup): void {
 		if (this.count < 2) {
 			return; // require at least 2 groups to show
 		}
@@ -384,6 +384,8 @@ export class EditorPart extends Part implements IEditorPart, IEditorGroupsView {
 			return; // we have not been created yet
 		}
 
+		const groupView = this.assertGroupView(target);
+
 		switch (arrangement) {
 			case GroupsArrangement.EVEN:
 				this.gridWidget.distributeViewSizes();
@@ -392,16 +394,16 @@ export class EditorPart extends Part implements IEditorPart, IEditorGroupsView {
 				if (this.groups.length < 2) {
 					return; // need at least 2 groups to be maximized
 				}
-				this.gridWidget.maximizeView(target);
-				target.focus();
+				this.gridWidget.maximizeView(groupView);
+				groupView.focus();
 				break;
 			case GroupsArrangement.EXPAND:
-				this.gridWidget.expandView(target);
+				this.gridWidget.expandView(groupView);
 				break;
 		}
 	}
 
-	toggleMaximizeGroup(target: IEditorGroupView = this.activeGroup): void {
+	toggleMaximizeGroup(target: IEditorGroupView | GroupIdentifier = this.activeGroup): void {
 		if (this.hasMaximizedGroup()) {
 			this.unmaximizeGroup();
 		} else {
@@ -409,7 +411,7 @@ export class EditorPart extends Part implements IEditorPart, IEditorGroupsView {
 		}
 	}
 
-	toggleExpandGroup(target: IEditorGroupView = this.activeGroup): void {
+	toggleExpandGroup(target: IEditorGroupView | GroupIdentifier = this.activeGroup): void {
 		if (this.isGroupExpanded(this.activeGroup)) {
 			this.arrangeGroups(GroupsArrangement.EVEN);
 		} else {
@@ -419,8 +421,7 @@ export class EditorPart extends Part implements IEditorPart, IEditorGroupsView {
 
 	private unmaximizeGroup(): void {
 		this.gridWidget.exitMaximizedView();
-		// When making views visible the focus can be affected, so restore it
-		this._activeGroup.focus();
+		this._activeGroup.focus(); // When making views visible the focus can be affected, so restore it
 	}
 
 	private hasMaximizedGroup(): boolean {
diff --git a/src/vs/workbench/browser/parts/editor/editorParts.ts b/src/vs/workbench/browser/parts/editor/editorParts.ts
index 0626bb73af6b9..06fd698bcd108 100644
--- a/src/vs/workbench/browser/parts/editor/editorParts.ts
+++ b/src/vs/workbench/browser/parts/editor/editorParts.ts
@@ -16,6 +16,7 @@ import { IInstantiationService } from 'vs/platform/instantiation/common/instanti
 import { IAuxiliaryWindowOpenOptions, IAuxiliaryWindowService } from 'vs/workbench/services/auxiliaryWindow/browser/auxiliaryWindowService';
 import { ILifecycleService } from 'vs/workbench/services/lifecycle/common/lifecycle';
 import { WindowTitle } from 'vs/workbench/browser/parts/titlebar/windowTitle';
+import { distinct } from 'vs/base/common/arrays';
 
 export class EditorParts extends Disposable implements IEditorGroupsService, IEditorPartsView {
 
@@ -228,8 +229,14 @@ export class EditorParts extends Disposable implements IEditorGroupsService, IEd
 
 	getGroups(order = GroupsOrder.CREATION_TIME): IEditorGroupView[] {
 		if (this._parts.size > 1) {
-			// TODO@bpasero support non-creation-time group orders across parts
-			return [...this._parts].map(part => part.getGroups(order)).flat();
+			let parts: EditorPart[];
+			if (order === GroupsOrder.MOST_RECENTLY_ACTIVE) {
+				parts = distinct([this.activePart, ...this._parts]); // put active part first in this order
+			} else {
+				parts = this.parts;
+			}
+
+			return parts.map(part => part.getGroups(order)).flat();
 		}
 
 		return this.mainPart.getGroups(order);
@@ -260,15 +267,15 @@ export class EditorParts extends Disposable implements IEditorGroupsService, IEd
 		this.getPart(group).setSize(group, size);
 	}
 
-	arrangeGroups(arrangement: GroupsArrangement, group?: IEditorGroupView): void {
+	arrangeGroups(arrangement: GroupsArrangement, group?: IEditorGroupView | GroupIdentifier): void {
 		(group !== undefined ? this.getPart(group) : this.activePart).arrangeGroups(arrangement, group);
 	}
 
-	toggleMaximizeGroup(group?: IEditorGroupView): void {
+	toggleMaximizeGroup(group?: IEditorGroupView | GroupIdentifier): void {
 		(group !== undefined ? this.getPart(group) : this.activePart).toggleMaximizeGroup(group);
 	}
 
-	toggleExpandGroup(group?: IEditorGroupView): void {
+	toggleExpandGroup(group?: IEditorGroupView | GroupIdentifier): void {
 		(group !== undefined ? this.getPart(group) : this.activePart).toggleExpandGroup(group);
 	}