Description:
On high DPI screen (like a 2k screen), drop down arrows are blurry.
The resulted UI is ugly and different from the demo screenshot of Notebookbar from https://blog.documentfoundation.org/blog/2018/06/05/libreoffice-interview-andreas-kainz-talks-about-new-icons-and-the-notebookbar/.


Steps to Reproduce:
Make sure OpenGL enabled and start LibreOffice

Actual Results:
Drop down arrows are blurry

Expected Results:
Drop down arrows are clear


Reproducible: Always


User Profile Reset: Yes


OpenGL enabled: Yes

Additional Info:
Version: 6.3.5.2 (x64)
Build ID: dd0751754f11728f69b42ee2af66670068624673
CPU threads: 12; OS: Windows 10.0; UI render: default; VCL: win; 
Locale: en-US (en_US); UI-Language: en-US
Calc: CL