Added a setting for configuring open direction for "open to the side" (#49523)

src/vs/workbench/common/editor.ts

@@ -772,6 +772,7 @@ export interface IWorkbenchEditorPartConfiguration {
 	enablePreviewFromQuickOpen?: boolean;
 	closeOnFileDelete?: boolean;
 	openPositioning?: 'left' | 'right' | 'first' | 'last';
+	openToTheSideDirection?: 'left' | 'right' | 'up' | 'down';
 	revealIfOpen?: boolean;
 	swipeToNavigate?: boolean;
 	labelFormat?: 'default' | 'short' | 'medium' | 'long';

src/vs/workbench/electron-browser/main.contribution.ts

@@ -212,6 +212,12 @@ configurationRegistry.registerConfiguration({
 			'default': 'right',
 			'description': nls.localize({ comment: ['This is the description for a setting. Values surrounded by single quotes are not to be translated.'], key: 'editorOpenPositioning' }, "Controls where editors open. Select 'left' or 'right' to open editors to the left or right of the currently active one. Select 'first' or 'last' to open editors independently from the currently active one.")
 		},
+		'workbench.editor.openToTheSideDirection': {
+			'type': 'string',
+			'enum': ['left', 'right', 'up', 'down'],
+			'default': 'right',
+			'description': nls.localize('openToTheSideDirection', "Controls where editors opened through the Open to Side option open. ")
+		},
 		'workbench.editor.revealIfOpen': {
 			'type': 'boolean',
 			'description': nls.localize('revealIfOpen', "Controls if an editor is revealed in any of the visible groups if opened. If disabled, an editor will prefer to open in the currently active editor group. If enabled, an already opened editor will be revealed instead of opened again in the currently active editor group. Note that there are some cases where this setting is ignored, e.g. when forcing an editor to open in a specific group or to the side of the currently active group."),

src/vs/workbench/services/editor/browser/nextEditorService.ts

@@ -269,7 +269,17 @@ export class NextEditorService extends Disposable implements INextEditorService
 	}
 
 	private createSideBySideGroup(): INextEditorGroup {
-		return this.nextEditorGroupsService.addGroup(this.nextEditorGroupsService.activeGroup, GroupDirection.RIGHT); // TODO@grid this should use an existing side group if there is one
+		const direction = this.configurationService.getValue<'left' | 'right' | 'up' | 'down'>('workbench.editor.openToTheSideDirection');
+
+		let groupDirection: GroupDirection = GroupDirection.RIGHT;
+		switch (direction) {
+			case 'left': groupDirection = GroupDirection.LEFT; break;
+			case 'right': groupDirection = GroupDirection.RIGHT; break;
+			case 'up': groupDirection = GroupDirection.UP; break;
+			case 'down': groupDirection = GroupDirection.DOWN; break;
+			default: groupDirection = GroupDirection.RIGHT;
+		}
+		return this.nextEditorGroupsService.addGroup(this.nextEditorGroupsService.activeGroup, groupDirection);
 	}
 
 	private toOptions(options?: IEditorOptions | EditorOptions): EditorOptions {