Upload Popup dialog positioning

I am integrating into a site that has a masterpage and theme.  I have added the control to a 'contentplaceholder' and all is well.  

My issue is that when I click the "upload" button - the upload backdrop and dialog box do not align with the control.  I am assuming the positioning error is coming through the use of the contentplaceholder. 

Please advise how I could modify, upload.aspx to adjust its positioning relative to the control.  Or there may be  a change needed in a .css file.

Also having this issue, unfortunately I'm stuck with non-standard HTML in my app. The div modalDialogPageMask is absolutely positioned presumably using some client side JavaScript. Not sure what element it's being positioned against.

My  fix was to override a couple of the FileVista Controls CSS values, which depending on the situation will let you compensate for the issue in your own CSS, something like the following;

.modalDialogPageMask {
    position:relative !important;
    left: auto !important;
    top: auto !important;
}
.modalDialog {
    margin-top:-25px !important; /*Adjust as appropriate*/
    margin-left:-25px !important; /*Adjust as appropriate*/
}

You might also want to use margin's to adjust the value in the pagemask rather than set positioning. Not great, but it works so far...