Description:
Text fields that contain no text but have a fill colour are visible in the editing view but not when presented.

Steps to Reproduce:
1. Create a text field (F2), add some text
2. Change the fill colour of the text field to any colour
3. Remove the text from the text field

Actual Results:
The text field is now only visible in the "Normal" view but invisible in the preview sidebar and when presenting.This is counter-intuitive, because after copying and pasting text fields it's not immediately clear whether they are text fields (and thus disappears) or rectangles inserted through the shapes tool.

Expected Results:
Display the text field as a colourful rectangle in the presentation or do not allow text fields without text.


Reproducible: Always


User Profile Reset: Yes


OpenGL enabled: Yes

Additional Info:
Version: 6.4.6.2
Build-ID: 1:6.4.6-0ubuntu0.20.04.1
CPU-Threads: 4; BS: Linux 5.4; UI-Render: GL; VCL: kf5; 
Gebietsschema: de-DE (de_DE.UTF-8); UI-Sprache: de-DE
Calc: threaded