Always post 'upload' param when attempting to upload a file

htdocs/artefact/file/form/elements/filebrowser.php

@@ -243,7 +243,7 @@ function pieform_element_filebrowser_doupdate(Pieform $form, $element) {
             'folder' => $folder,
         ));
     }
-    else if (!empty($_POST['upload']) || (isset($_FILES['userfile']))) {
+    else if (!empty($_POST['upload'])) {
         if (!isset($_FILES['userfile']['name'])) {
             return array(
                 'error'   => true,

htdocs/artefact/file/js/filebrowser.js

@@ -31,6 +31,9 @@ function FileBrowser(idprefix, folderid, config, globalconfig) {
             setNodeAttribute(self.id + '_userfile', 'disabled', true);
             addElementClass(self.id + '_uploadcancel', 'hidden');
         }
+        if (!self.form.upload) {
+            appendChildNodes(self.form, INPUT({'type':'hidden','name':'upload','value':0}));
+        }
         self.upload_connectbuttons();
     }
 
@@ -85,11 +88,13 @@ function FileBrowser(idprefix, folderid, config, globalconfig) {
         }
 
         self.upload_presubmit();
+        self.form.upload.value = 1;
         signal(self.form, 'onsubmit');
         self.form.submit();
         // $(self.id + '_userfile').value = ''; // Won't work in IE
         replaceChildNodes(self.id + '_userfile_container', INPUT({'type':'file', 'class':'file', 'id':self.id+'_userfile', 'name':'userfile', 'size':40}));
         connect(self.id + '_userfile', 'onchange', self.upload_submit);
+        self.form.upload.value = 0;
         return false;
     }