HTML: Select all

  <select name="list" id="list">
    <option value="1">Selection1</option>
    <option value="2">Selection2</option>
    <option value="...">...</option>
  </select>

That is how you produce drop down boxes with HTML.

To open a file, you can upload it to your servver via a HTML form and then manipulate the handling of the file with ASP.NET.
E.G. UploadForm.aspx has a form, you browse to the text file you want to upload you submit this form to Upload.aspx.
Upload.aspx takes the file and moves it somewhere for safe keeping, and then you can do whatever you want with the file.

Copy and Paste? You don't need anything to copy and paste (ctrl +c = copy; ctrl + v= paste) but if you want to have a button which the user clicks to paste their clipboard into a textbox or something I found this javascript:

Code: Select all

<script>  
 
function a2kpaste() {  
     var rng = document.selection.createRange();  
     rng.execCommand("paste");  
}  
</script>