Ooops, sorry. Wrong thread.

@RedFarmer i have trouble with the 1280x1024... the game field aspect ratio is not right... the cfg is not working original resolution was 160x144px which is 1:1.111 but your version is is almost 1:1. I think ill try a different one or convert one 16:9 myself

@mitu thanks for the tip! Its definitely useful info if there will be some problems with positioning image on screen, Ill save this video for later use. Actually I found another solution for the problem: before the game starts there is a grey info box, you can push some button and then enter a menu with additional setting. From there you can enter default video resolution submenu and play a little with setting that are stored there. I managed to fit image to the screen at 800x600 4:3 setting. It works with both psx and snes emulation. Maybe this info also would be usefull for someone. Thank again and good luck!

@Garisaan i have done something sort of like this here: https://retropie.org.uk/forum/topic/4046/crt-pi-shader-users-reduce-scaling-artifacts-with-these-configs-in-lr-mame2003-lr-fbalpha-lr-nestopia-and-more-to-come if you use the last two links in that post, it will give you crt-pi-curvature-vertical shader in vertical mame games, and the regular curvature shader in the rest.

Sorry just saw a dedicated thread by @meleu about this very thing. Please close :)

@ruckage :Oh my god! You just made my entire month!

@dankcushions Thanks for the tip, I changed the setting to 5:4via the Configuration Editor, that then made the changes to the retroarch.cfg file and that's now the default when I load games. Interesting that by changing it manually it did not work. Anyway, thanks again for all the help over the past few days. I hope this thread is useful for someone else one day who also wants to use a CRT and really wants fullscreen :)