Hi,
when LibreOffice Writer exports to a PDF file and the content includes form objects like textfields, they do have borders in the PDF.
I don’t want the bordered or flat version in the PDF. Just the standard looking background color that signals its a form field.
But if I disable the border, its so hard to detect in the editor:
Why is that?
Do I understand your question correctly?
You want to know why a text field with a white background on a white sheet is not easily visible in editor mode?
What problem do you really have with it?
Yes.
The problem is, that I don’t see them when editing. So if I want to edit a specific textfield, I wont find it and therefore can not click on it.
It is a bit of an odd behavior, because if you choose no borders on a table, LO Writer still shows fine greyish lines so that the user knows: There is a table and this are it’s dimensions.
Not so on borderless form controls.
For these cases you should use the Navigator.
In the navigator, for example, double-click on “Control x” and you are there.
Interestingly, jump to Navigator control objects does not work, if you aren’t in design mode.
Anyway, I thought that might be just a display error on my side, but I think otherwise showing borderless control objects like borderless tables are an visual improvement to Writer. 
Here is another workaround.
The page you work on will have the background but it won’t print nor export to pdf.
…if you aren’t in design mode.
Yes, it’s the design mode.
With me:
Version: 7.4.2.3 (x64) / LibreOffice Community
Build ID: 382eef1f22670f7f4118c8c2dd222ec7ad009daf
CPU threads: 8; OS: Windows 10.0 Build 19045; UI render: Skia/Raster; VCL: win
Locale: de-DE (de_DE); UI: de-DE
Calc: CL
