Can diacritic character emboldening be turned off?

[howardpc]

If I open a Greek text file in the editor, unadorned characters (γ α ρ ε etc.) are shown in a normal typeface.
However characters with accents (Ἐ ὰ ἀ ῆ ῖ etc.) are shown in bold, even though the context menu File Settings->Highlighter is set to None.
Is there some way of altering this 'default' display mode so that none of the text is shown bold?

[Ñuño_Martínez]

I did some testing and this looks like a text font issue.  The font you're using (Courier new?) doesn't have that characters so the editor looks them in a different text font (i.e. system default one).  So it isn't rendering them boded but it is rendering them with another text font.

Go to Tools > Options... > Editor > Display and change the Default editor font to another one that have the characters you need (for example, Courier 10 Pitch or DejaVu Sans Mono).