The "mark" parameter in the OnGutterClick event is always showing as Nil.
I'm using the example lazarus project SynGutterMarkExample to create the marks. The code below shows how I catch the vent.
(The X,Y values seem valid though. So I can work from that if I have to I guess.)
procedure TForm1.SynEdit1GutterClick(Sender: TObject; X, Y, Line: integer;
mark: TSynEditMark);
begin
if ( mark = nil ) then begin
beep; // this always fires
end;
end;