Dropdown box filter

You can use Lookup wizard option 'Edit box with AJAX popup' for this purpose.

Sergey, thank you for your reply. My problem: I table a list of pdf files (located in the upload folder). The following table is a record which may remain for several pdf files. Files to show I set as the URL link. Using the AJAX popup, I dont have option add multiple files to a record, and there is still open the window to insert pdf files only from your local PC. My idea is that when I enter the record, it would show me a list in the database and if there is not the desired pdf file, I add it on the fly and of course I have a choice of several pdf files using the Ctrl / Shift. This all works perfectly using the dropdown box. But when the pdf files will be many, the problem will find a specific pdf file. Any Idea?
P.S. There is also another problem: if I select multiple files, I can see the preview file names separated by commas, but the URL link is only one with the names of all attached files

Edit: The problem is tabel_list.php in table_view.php view is correct.

I see what you saying. Unfortunately right now we do not have an option to filter multi-select listbox. This is something that we going to add shortly.
I'm not 100% sure I understand the second issue. Do you have a live URL that can explain what the issue is?

Hi!
From the images it will be clear. OneUrl.png image is generated from file_list.php (http://files/DokuOne.pdf,DokuTwo.pdf'>http://files/DokuOne.pdf,DokuTwo.pdf) and TwoUrl.png is generated from file_view.php (http://files/DokuOne.pdf and http://files/DokuTwo.pdf).

Unfortunately it's not clear.
I would ask you to post your application to Demo Account and open a ticket at http://support.xlinesoft.com sending your Demo Account URL. 'Demo Account' button can be found on the last screen in the program.
PS. Probably you going to use 'View as' type 'Custom' in this case to build proper links. Still need to see your app first.