Hello Jan, hope you feel great!
I have again ideas for improvements.
small and fairly simple
1. A little pop up delay for the ground supply panel.
At the moment, when i click on the cround call button, i hear a beep and the ground handling panel pops up emediatly. i´m too lazy to hold the butten for a realistic dedldedldedldedl as the popup ist already there anyways. So i think it would be nice if you have to hold the button for a second or two, in order to activate the popup and let the horn scream for a little bit. in reality the cround crew takes a little time for responding as well ^^.
to be honest...it really took me a while to realize there is moore then just a "beep" because i never held the button pushed.
2. crew call button "ding"
if i want to give a "ding" to the cabin crew, i always have to close the crew options window afterwards as it pops up just after you click the button. so maby you could programm it in a way, that a simple click splays the sound, and a double click or a held click toggles the window.
3. maby as an Option, the brown collored screens you showed in the W.I.P. pictures. i think many 737-CLs have them nowdays as they are often replaced by 757/767 screens since the originals aren´t the newest anymore.
4.never gonna make it into yout "to do" list, but i´ll suggest it anyways. who knows.
digital VSI indicators, as they are sometimes found as aftermarket installations.
Greetings from Hamburg in Germany
Have a great day!