It seems that Drag and Drop function of the AjaxFileUpload control is not working on IE10 (tested in IE10 for Windows 7).
For example the official sample (just try it yourself : http://www.asp.net/ajaxLibrary/AjaxControlToolkitSampleSite/AjaxFileUpload/AjaxFileUpload.aspx) is working well in Chrome and Firefox, but not in IE10.
For example the official sample (just try it yourself : http://www.asp.net/ajaxLibrary/AjaxControlToolkitSampleSite/AjaxFileUpload/AjaxFileUpload.aspx) is working well in Chrome and Firefox, but not in IE10.