*** This is a spin-off of issue 31197 ***

With issue 31197 being fixed, it's now possible to export form controls to PDF
as *controls* (instead of simple drawings).
However, submit buttons seem not to work currently:
- open the attached bug doc. It contains two buttons, one being exported as PDF
Reset
  button, and one being exported as Submit button
- export it to PDF
- open the resulting in Acrobat Reader (looking into it, it seems my reader is
somewhat
  old: it's a 4.0 ...)
=> The "gray" and the "green" input field do not show text. Only clicking into the
   controls reveals their text
=> You cannot focus the "cyan" edit field: When you try to click into it,
nothing happens

Both effects really depend on the submit button only. To prove this
- open the original document
- select the submit button
- chose "Form..." from it's context menu
- in the property browser which opens then, reset the "URL" property to an empty
string
- export as PDF, again
=> the resulting PDF document does not show the problems above.