I understand that it is good practice not to indent the first paragraph after a section. LyX indeed shows it as not indented. But in this case, the UI "guesses wrong", and under paragraph properties, the "indent paragraph" check box is ticked. Then, on preview, the 1st paragraph _is_ indented.
This can be corrected by unchecking the relevant box, but why doesn't the GUI reflect properly this setting? I wonder if perhaps it is a side effect of the language settings (my documents are in French). Thank you for any input - regards, -- Daniel CLEMENT