Address comments

src/vs/base/parts/quickopen/browser/quickOpenWidget.ts

@@ -244,7 +244,8 @@ export class QuickOpenWidget implements IModelProvider {
 						alwaysFocused: true,
 						verticalScrollMode: ScrollbarVisibility.Visible,
 						ariaLabel: nls.localize('treeAriaLabel', "Quick Picker"),
-						keyboardSupport: this.options.keyboardSupport
+						keyboardSupport: this.options.keyboardSupport,
+						preventRootFocus: true
 					});
 
 				this.treeElement = this.tree.getHTMLElement();

src/vs/base/parts/tree/browser/tree.ts

@@ -670,6 +670,7 @@ export interface ITreeOptions extends ITreeStyles {
 	paddingOnRow?: boolean;
 	ariaLabel?: string;
 	keyboardSupport?: boolean;
+	preventRootFocus?: boolean;
 }
 
 export interface ITreeStyles {

src/vs/base/parts/tree/browser/treeView.ts

@@ -444,7 +444,9 @@ export class TreeView extends HeightMap {
 
 		this.domNode = document.createElement('div');
 		this.domNode.className = `monaco-tree no-focused-item monaco-tree-instance-${this.instance}`;
-		this.domNode.tabIndex = container.className === 'quick-open-tree' ? -1 : 0;
+		if (!context.options.preventRootFocus) {
+			this.domNode.tabIndex = 0;
+		}
 
 		this.styleElement = DOM.createStyleSheet(this.domNode);