drag/drop support

wv-element.rkt

@@ -88,6 +88,40 @@
     (define/public (attr/datetime attr)
       (webview-attr/datetime wv element-id attr))
 
+    (define/public (draggable! yes-no . on-drag)
+      (webview-set-attr! wv element-id "draggable" yes-no)
+      (if (eq? yes-no #f)
+          (send window unbind! element-id 'ondragstart)
+          (if (null? on-drag)
+              (error "Need an on-drag handler (λ (el) ...)")
+              (send window bind! element-id 'ondragstart
+                    (λ (el evt data) ((car on-drag) el)))
+              )
+          )
+      )
+
+    (define/public (droppable! yes-no . on-drop)
+      (if (eq? yes-no #f)
+          (send window unbind! element-id 'ondrop)
+          (if (null? on-drop)
+              (error "Need an on-drop handler (λ (el) ...)")
+              (send window bind! element-id 'ondrop
+                    (λ (el evt data) ((car on-drop) el)))
+              )
+          )
+      )
+
+    (define/public (dragover! yes-no . on-dragover)
+      (if (eq? yes-no #f)
+          (send window unbind! element-id 'ondragover)
+          (if (null? on-dragover)
+              (error "Need an on-dragover handler (λ (el) ...)")
+              (send window bind! element-id 'ondragover
+                    (λ (el evt data) ((car on-dragover) el)))
+              )
+          )
+      )
+
     (define/public (focus!)
       (let ((s (js (let* ((el (send document getElementById (eval element-id))))
                      (if (=== el null)