... Nov 2019 15:05 by Graeme posted: 29 Nov 2019 22:21 from: Martin Wynne Hi Graeme, Did you forget to include switch_select.lfm in your post? You are referencing a component switch_info:TMemo; which isn't on the existing form, so not surprisingly all I'm getting is an AV when clicking the button. I'm a bit surprised that the Lazarus compiler isn't complaining about it. I'm finding your indenting style: begin if check_valid_switch_selected=False then EXIT; // no switch or no data for it. if switch_info_showing=True then begin show_info_button.Caption := 'show switch info'; resize_small(); switch_info_showing := False; end else begin show_switch_info(full_size_mm_radiobutton.Checked, switch_info_showing); show_info_button.Caption := 'hide switch info'; resize_big(); switch_info_showing := True; end; // ??? Is this next line required? ??? if switch_selector_listbox.Visible then switch_selector_listbox.SetFocus; end; very difficult to follow. I realise I will need to be flexible and less set in my ways for a collaborative project, but I'm wondering if ...