src/vs/workbench/contrib/mergeEditor/browser/view/mergeEditor.ts/MergeEditorOpenHandlerContribution/openCodeEditorFromMergeEditor
class MergeEditorOpenHandlerContribution:	private async openCodeEditorFromMergeEditor(input: ITextResourceEditorInput, _source: ICodeEditor | null, sideBySide?: boolean | undefined): Promise<ICodeEditor | null> {
		const activePane = this._editorService.activeEditorPane;
		if (!sideBySide
			&& input.options
			&& activePane instanceof MergeEditor
			&& activePane.getControl()
			&& activePane.input instanceof MergeEditorInput
			&& isEqual(input.resource, activePane.input.result)
		) {
			// Special: stay inside the merge editor when it is active and when the input
			// targets the result editor of the merge editor.
			const targetEditor = <ICodeEditor>activePane.getControl()!;
			applyTextEditorOptions(input.options, targetEditor, ScrollType.Smooth);
			return targetEditor;
		}

		// cannot handle this
		return null;
	}