Revert "fixes #3294"

This reverts commit 16a8d1d1.

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

@@ -808,7 +808,7 @@ export class TreeModel extends Events.EventEmitter {
 			this.addEmitter2(this.registry),
 			this.registry.addListener2('item:dispose', (event: IItemDisposeEvent) => {
 				event.item.getAllTraits()
-					.forEach(trait => this.removeTraits(trait, [event.item]));
+					.forEach(trait => delete this.traitsToItems[trait][event.item.id]);
 			})
 		);
 
@@ -1126,6 +1126,8 @@ export class TreeModel extends Events.EventEmitter {
 
 	public setFocus(element?: any, eventPayload?: any): void {
 		this.setTraits('focused', element ? [element] : []);
+		var eventData: _.IFocusEvent = { focus: this.getFocus(), payload: eventPayload };
+		this.emit('focus', eventData);
 	}
 
 	public isFocused(element: any): boolean {

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

@@ -330,10 +330,6 @@ export class ViewItem implements IViewItem {
 		this.row = null;
 	}
 
-	hasDOMFocus(): boolean {
-		return this.row && this.row.element && DOM.isAncestor(document.activeElement, this.row.element);
-	}
-
 	public dispose(): void {
 		this.row = null;
 		this.model = null;
@@ -728,6 +724,9 @@ export class TreeView extends HeightMap implements IScrollable {
 				case 'item:removeTrait':
 					this.onItemRemoveTrait(data);
 					break;
+				case 'focus':
+					this.onModelFocusChange();
+					break;
 			}
 		}
 
@@ -1072,10 +1071,6 @@ export class TreeView extends HeightMap implements IScrollable {
 				}
 			}
 		}
-
-		if (e.trait === 'focused') {
-			setTimeout(() => this.onModelFocusChange());
-		}
 	}
 
 	private onItemRemoveTrait(e:Model.IItemTraitEvent): void {
@@ -1094,10 +1089,6 @@ export class TreeView extends HeightMap implements IScrollable {
 			}
 			delete this.highlightedItemWasDraggable;
 		}
-
-		if (e.trait === 'focused') {
-			setTimeout(() => this.onModelFocusChange());
-		}
 	}
 
 	private onModelFocusChange(): void {
@@ -1610,10 +1601,6 @@ export class TreeView extends HeightMap implements IScrollable {
 	}
 
 	private removeItemFromDOM(item: ViewItem): void {
-		if (item.hasDOMFocus()) {
-			this.focus();
-		}
-
 		item.removeFromDOM();
 	}