fixes #59218

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

@@ -346,7 +346,7 @@ export class ListView<T> implements ISpliceable<T>, IDisposable {
 
 	@memoize get onMouseClick(): Event<IListMouseEvent<T>> { return filterEvent(mapEvent(domEvent(this.domNode, 'click'), e => this.toMouseEvent(e)), e => e.index >= 0); }
 	@memoize get onMouseDblClick(): Event<IListMouseEvent<T>> { return filterEvent(mapEvent(domEvent(this.domNode, 'dblclick'), e => this.toMouseEvent(e)), e => e.index >= 0); }
-	@memoize get onMouseMiddleClick(): Event<IListMouseEvent<T>> { return filterEvent(mapEvent(domEvent(this.domNode, 'auxclick'), e => this.toMouseEvent(e)), e => e.index >= 0); }
+	@memoize get onMouseMiddleClick(): Event<IListMouseEvent<T>> { return filterEvent(mapEvent(domEvent(this.domNode, 'auxclick'), e => this.toMouseEvent(e)), e => e.index >= 0 && e.browserEvent.button === 1); }
 	@memoize get onMouseUp(): Event<IListMouseEvent<T>> { return filterEvent(mapEvent(domEvent(this.domNode, 'mouseup'), e => this.toMouseEvent(e)), e => e.index >= 0); }
 	@memoize get onMouseDown(): Event<IListMouseEvent<T>> { return filterEvent(mapEvent(domEvent(this.domNode, 'mousedown'), e => this.toMouseEvent(e)), e => e.index >= 0); }
 	@memoize get onMouseOver(): Event<IListMouseEvent<T>> { return filterEvent(mapEvent(domEvent(this.domNode, 'mouseover'), e => this.toMouseEvent(e)), e => e.index >= 0); }

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

@@ -551,7 +551,11 @@ export class TreeView extends HeightMap {
 		this.viewListeners.push(DOM.addDisposableListener(this.domNode, 'keyup', (e) => this.onKeyUp(e)));
 		this.viewListeners.push(DOM.addDisposableListener(this.domNode, 'mousedown', (e) => this.onMouseDown(e)));
 		this.viewListeners.push(DOM.addDisposableListener(this.domNode, 'mouseup', (e) => this.onMouseUp(e)));
-		this.viewListeners.push(DOM.addDisposableListener(this.wrapper, 'auxclick', (e) => this.onMouseMiddleClick(e)));
+		this.viewListeners.push(DOM.addDisposableListener(this.wrapper, 'auxclick', (e: MouseEvent) => {
+			if (e && e.button === 1) {
+				this.onMouseMiddleClick(e);
+			}
+		}));
 		this.viewListeners.push(DOM.addDisposableListener(this.wrapper, 'click', (e) => this.onClick(e)));
 		this.viewListeners.push(DOM.addDisposableListener(this.domNode, 'contextmenu', (e) => this.onContextMenu(e)));
 		this.viewListeners.push(DOM.addDisposableListener(this.wrapper, Touch.EventType.Tap, (e) => this.onTap(e)));