WebListBox font different

Has anybody noticed the font difference between WebTextFields/WebTextArea and WebListBox.
My system font is sans serif and the font in the WebListBox is serif and therefore not the same as my system font.

I have checked it with Xojo 2018r4 and Xojo 2019r1.1 (only the standard Xojo plugins installed).
The font in WebListBox is different in macOS but fine in Windows.
Tested in Safari, Firefox and Edge.