0. install latest TSplus version 11.50.8.27
   if you miss that step then following steps will be useless.
   (after installation reboot is mandatory)

2. you get two files, webime.ini and file_picker_pdf.au3

3.1. (That step is not necessary if you don't want to start your specific program for each successful file upload to server) 
   place webime.ini to your TSplus directory in same directory with webime.exe
   that is usually *\TSplus\UserDesktop\files\webime.exe so that you get *\TSplus\UserDesktop\files\webime.ini

3.2. (That step is not necessary if you don't want to start your specific program for each successful file upload to server) 
   edit that webime.ini file with Notepad and change path to wished program that will be started for each uploaded file by passing its full path to this executable

   [onFileCopyRun]
   myRunProgHolder=C:\progs\message.exe

   where myRunProgHolder is the unique name to distinguish different file handlers if wished, and then the path to wished program to be started.

4. now download and install Autoit from https://www.autoitscript.com/site/autoit/downloads/, you need Autoit to compile *.au3 to exe.

5.you can adjust parameters inside file_picker_pdf.au3 whith already predefined value
   *****W.mainUploadCenter([ 0, '', '|*.pdf|', 'myRunProgHolder' ]);****
   where "myRunProgHolder" is wished path-name-holder matching entry as given in webime.ini
   (If you don't want to start your specific program for each file upload then remove 'myRunProgHolder' like in example
   *****W.mainUploadCenter([ 0, '', '|*.pdf|', '' ]);****) 

In that example is used pdf extension for default browsers filter. As example |*.pdf| means pdf extension, or |*.pdf|*.txt| would mean pdf and txt extension.
Remember here, the extension filter has in browsers no imperative character but just default advising for browser to prefer wished extensions, so it would not prohobit another extensions to choose, however they won't be directly accepted. Supported that extension filter feature is only in FF and Chrome, but not in IE.

10. compile that script file_picker_pdf.au3 to executable with Autoit, most easy with right click on script and "Compile script"
You can now execute this executable inside session, it will send JavaScript message to browser, and if you have good connection timing and the command arrives during one second time frame, then browsers like FF and Chrome will accept such command as privileged action and you should see after ~1 second browsers file choice menu.
If you miss that one second frame, or execute program not by mouse click, but as example by keyboard enter button, or you use browser like Internet Explorer 
where is no such one second posponed privileged onclick handling implemented then you will get message that will tell you to click on it to 
finally call the file choice menu.
