fix some dnd issues after getting feedback

src/vs/workbench/browser/dnd.ts

@@ -373,7 +373,10 @@ export function fillResourceDataTransfers(accessor: ServicesAccessor, resources:
 	}
 
 	// Resource URLs: allows to drop multiple resources to a target in VS Code (not directories)
-	event.dataTransfer.setData(DataTransfers.RESOURCES, JSON.stringify(sources.filter(s => !s.isDirectory).map(s => s.resource.toString())));
+	const files = sources.filter(s => !s.isDirectory);
+	if (files.length) {
+		event.dataTransfer.setData(DataTransfers.RESOURCES, JSON.stringify(files.map(f => f.resource.toString())));
+	}
 
 	// Editors: enables cross window DND of tabs into the editor area
 	const textFileService = accessor.get(ITextFileService);
@@ -381,7 +384,7 @@ export function fillResourceDataTransfers(accessor: ServicesAccessor, resources:
 	const editorService = accessor.get(IWorkbenchEditorService);
 
 	const draggedEditors: ISerializedDraggedEditor[] = [];
-	sources.forEach(source => {
+	files.forEach(file => {
 
 		// Try to find editor view state from the visible editors that match given resource
 		let viewState: IEditorViewState;
@@ -391,7 +394,7 @@ export function fillResourceDataTransfers(accessor: ServicesAccessor, resources:
 			const codeEditor = getCodeEditor(editor);
 			if (codeEditor) {
 				const model = codeEditor.getModel();
-				if (model && model.uri && model.uri.toString() === source.resource.toString()) {
+				if (model && model.uri && model.uri.toString() === file.resource.toString()) {
 					viewState = codeEditor.saveViewState();
 					break;
 				}
@@ -400,13 +403,15 @@ export function fillResourceDataTransfers(accessor: ServicesAccessor, resources:
 
 		// Add as dragged editor
 		draggedEditors.push({
-			resource: source.resource.toString(),
-			backupResource: textFileService.isDirty(source.resource) ? backupFileService.toBackupResource(source.resource).toString() : void 0,
+			resource: file.resource.toString(),
+			backupResource: textFileService.isDirty(file.resource) ? backupFileService.toBackupResource(file.resource).toString() : void 0,
 			viewState
 		});
 	});
 
-	event.dataTransfer.setData(CodeDataTransfers.EDITORS, JSON.stringify(draggedEditors));
+	if (draggedEditors.length) {
+		event.dataTransfer.setData(CodeDataTransfers.EDITORS, JSON.stringify(draggedEditors));
+	}
 }
 
 /**

src/vs/workbench/parts/files/electron-browser/views/explorerViewer.ts

@@ -50,7 +50,7 @@ import { attachInputBoxStyler } from 'vs/platform/theme/common/styler';
 import { IThemeService } from 'vs/platform/theme/common/themeService';
 import { IWindowService } from 'vs/platform/windows/common/windows';
 import { IWorkspaceEditingService } from 'vs/workbench/services/workspace/common/workspaceEditing';
-import { extractResources, SimpleFileResourceDragAndDrop, CodeDataTransfers } from 'vs/workbench/browser/dnd';
+import { extractResources, SimpleFileResourceDragAndDrop, CodeDataTransfers, fillResourceDataTransfers } from 'vs/workbench/browser/dnd';
 import { relative } from 'path';
 import { distinctParents } from 'vs/base/common/resources';
 import { WorkbenchTree, WorkbenchTreeController } from 'vs/platform/list/browser/listService';
@@ -729,12 +729,14 @@ export class FileDragAndDrop extends SimpleFileResourceDragAndDrop {
 			});
 
 			// Apply some datatransfer types to allow for dragging the element outside of the application
-			super.onDragStart(tree, data, originalEvent);
+			this.instantiationService.invokeFunction(fillResourceDataTransfers, sources, originalEvent);
 
 			// The only custom data transfer we set from the explorer is a file transfer
 			// to be able to DND between multiple code file explorers across windows
 			const fileResources = sources.filter(s => !s.isDirectory && s.resource.scheme === Schemas.file).map(r => r.resource.fsPath);
-			originalEvent.dataTransfer.setData(CodeDataTransfers.FILES, JSON.stringify(fileResources));
+			if (fileResources.length) {
+				originalEvent.dataTransfer.setData(CodeDataTransfers.FILES, JSON.stringify(fileResources));
+			}
 		}
 	}
 

src/vs/workbench/parts/files/electron-browser/views/openEditorsView.ts

@@ -544,16 +544,16 @@ class OpenEditorRenderer implements IRenderer<OpenEditor, IOpenEditorTemplateDat
 		editorTemplate.toDispose = [];
 
 		editorTemplate.toDispose.push(dom.addDisposableListener(container, dom.EventType.DRAG_START, (e: DragEvent) => {
+			const dragged = <OpenEditor[]>this.getSelectedElements().filter(e => e instanceof OpenEditor && !!e.getResource());
 
 			const dragImage = document.createElement('div');
 			e.dataTransfer.effectAllowed = 'copyMove';
 			dragImage.className = 'monaco-tree-drag-image';
-			dragImage.textContent = editorTemplate.openEditor.editor.getName();
+			dragImage.textContent = dragged.length === 1 ? editorTemplate.openEditor.editor.getName() : String(dragged.length);
 			document.body.appendChild(dragImage);
 			e.dataTransfer.setDragImage(dragImage, -10, -10);
 			setTimeout(() => document.body.removeChild(dragImage), 0);
 
-			const dragged = <OpenEditor[]>this.getSelectedElements().filter(e => e instanceof OpenEditor && !!e.getResource());
 			this.transfer.setData(dragged, OpenEditor.prototype);
 
 			if (editorTemplate.openEditor && editorTemplate.openEditor.editor) {