TextArea.SelectionFontName
From Xojo Documentation
Property (As String )
aTextArea.SelectionFontName = newStringValue
or
StringValue = aTextArea.SelectionFontName
New in 2019r2
Supported for all project types and targets.
or
StringValue = aTextArea.SelectionFontName
New in 2019r2
Supported for all project types and targets.
Used to get and set the text font of the selected text.
Notes
When used in an unstyled TextArea, it changes the font of all the text in the TextArea.