If you're like me you have only written macros till now. I was so used to opening Menu> Tools Macros Organize Macros LibreOffice Basic... that I didn't even notice the menu choice right below it for Organize Dialogs... where you can create and edit dialogs.
When you open it up you get among other things the list of the largely undocumented LibreOffice Dialogs which is all read-only for some reason although it appears you can edit a dialog's properties. This is also where you can open My Dialogs and Dialogs for your other opened documents.
Be sure Menu> View Toolbars Toolbox is checked which gives you a menu of drag and drop tools.
Select something on the Dialog. Small green corners will appear. Also properties will appear with General and Events tabs.
The Events tab is where you link the Dialog to macros to create behavior. It seems you can't drag to move, but you can set the xy coordinates to adjust the Dialog. Also there is a preview button 
to preview your dialog. (Use Escape to close it again.)
When Regina writes in another answer here, "To see such dialog in action, simple run "StartChangeUserfields" in module Userfields in library "Gimmicks", the way you do this is to go to Menu> Tools Macros Run Macro Then drill down in LibreOffice Macros Gimmicks click Userfields and then StartChangeUserfields and hit the Run button.
Which gives you this Dialog which you can use to edit your use data.
Verify that this works by entering something like in Company name, and clicking Select below. Then to go a main LO window, and see Menu> Tools Options LibreOffice User Data.
