Fix button redraw issue (Resolves #15)

src/components/Button.js

@@ -35,6 +35,10 @@ export default class ButtonComponent {
     };
   }
 
+  onbeforeupdate(vnode) {
+    this.defaultProps.disabled = vnode.attrs.active === false;
+  }
+
   view(vnode) {
     return m(Button, { ...this.defaultProps, ...vnode.attrs });
   }

src/views/studydocs/studydocNew.js

@@ -133,6 +133,8 @@ export default class studydocNew {
           this.doc.files = e.target.files;
           if (this.doc.files.length > 0) {
             this.isValid = true;
+          } else {
+            this.isValid = false;
           }
         },
       }),