fixes #26184

extensions/git/src/commands.ts

@@ -132,7 +132,7 @@ export class CommandCenter {
 			return await commands.executeCommand<void>('vscode.open', right);
 		}
 
-		return await commands.executeCommand<void>('vscode.diff', left, right, title);
+		return await commands.executeCommand<void>('vscode.diff', left, right, title, { preview: true });
 	}
 
 	private getLeftResource(resource: Resource): Uri | undefined {

src/vs/base/browser/ui/list/listWidget.ts

@@ -321,6 +321,7 @@ class MouseController<T> implements IDisposable {
 		this.disposables = [];
 		this.disposables.push(view.addListener('mousedown', e => this.onMouseDown(e)));
 		this.disposables.push(view.addListener('click', e => this.onPointer(e)));
+		this.disposables.push(view.addListener('dblclick', e => this.onDoubleClick(e)));
 		this.disposables.push(view.addListener(TouchEventType.Tap, e => this.onPointer(e)));
 	}
 
@@ -362,6 +363,19 @@ class MouseController<T> implements IDisposable {
 		this.list.open(focus);
 	}
 
+	private onDoubleClick(e: IListMouseEvent<T>): void {
+		e.preventDefault();
+		e.stopPropagation();
+
+		if (isSelectionChangeEvent(e)) {
+			return;
+		}
+
+		const focus = this.list.getFocus();
+		this.list.setSelection(focus);
+		this.list.pin(focus);
+	}
+
 	private changeSelection(e: IListMouseEvent<T>, reference: number | undefined): void {
 		const focus = e.index;
 
@@ -574,6 +588,11 @@ export class List<T> implements ISpliceable<T>, IDisposable {
 		return mapEvent(this._onOpen.event, indexes => this.toListEvent({ indexes }));
 	}
 
+	private _onPin = new Emitter<number[]>();
+	@memoize get onPin(): Event<IListEvent<T>> {
+		return mapEvent(this._onPin.event, indexes => this.toListEvent({ indexes }));
+	}
+
 	private _onDOMFocus = new Emitter<void>();
 	get onDOMFocus(): Event<void> { return this._onDOMFocus.event; }
 
@@ -813,6 +832,10 @@ export class List<T> implements ISpliceable<T>, IDisposable {
 		this._onOpen.fire(indexes);
 	}
 
+	pin(indexes: number[]): void {
+		this._onPin.fire(indexes);
+	}
+
 	style(styles: IListStyles): void {
 		const content: string[] = [];
 

src/vs/workbench/parts/scm/electron-browser/scmViewlet.ts

@@ -25,6 +25,8 @@ import { VIEWLET_ID } from 'vs/workbench/parts/scm/common/scm';
 import { FileLabel } from 'vs/workbench/browser/labels';
 import { CountBadge } from 'vs/base/browser/ui/countBadge/countBadge';
 import { ISCMService, ISCMProvider, ISCMResourceGroup, ISCMResource } from 'vs/workbench/services/scm/common/scm';
+import { IEditorGroupService } from 'vs/workbench/services/group/common/groupService';
+import { IWorkbenchEditorService } from 'vs/workbench/services/editor/common/editorService';
 import { IInstantiationService } from 'vs/platform/instantiation/common/instantiation';
 import { IContextViewService, IContextMenuService } from 'vs/platform/contextview/browser/contextView';
 import { IContextKeyService } from 'vs/platform/contextkey/common/contextkey';
@@ -243,7 +245,9 @@ export class SCMViewlet extends Viewlet {
 		@IThemeService protected themeService: IThemeService,
 		@IMenuService private menuService: IMenuService,
 		@IModelService private modelService: IModelService,
-		@ICommandService private commandService: ICommandService
+		@ICommandService private commandService: ICommandService,
+		@IEditorGroupService private groupService: IEditorGroupService,
+		@IWorkbenchEditorService private editorService: IWorkbenchEditorService
 	) {
 		super(VIEWLET_ID, telemetryService, themeService);
 
@@ -320,6 +324,11 @@ export class SCMViewlet extends Viewlet {
 			.filter(e => !!e && isSCMResource(e))
 			.on(this.open, this, this.disposables);
 
+		chain(this.list.onPin)
+			.map(e => e.elements[0])
+			.filter(e => !!e && isSCMResource(e))
+			.on(this.pin, this, this.disposables);
+
 		this.list.onContextMenu(this.onListContextMenu, this, this.disposables);
 		this.disposables.push(this.list);
 
@@ -406,6 +415,12 @@ export class SCMViewlet extends Viewlet {
 			.done(undefined, onUnexpectedError);
 	}
 
+	private pin(): void {
+		const activeEditor = this.editorService.getActiveEditor();
+		const activeEditorInput = this.editorService.getActiveEditorInput();
+		this.groupService.pinEditor(activeEditor.position, activeEditorInput);
+	}
+
 	getTitle(): string {
 		const title = localize('source control', "Source Control");
 		const providerLabel = this.scmService.activeProvider && this.scmService.activeProvider.label;