I have to confess that I am old - and my eyes have been ravished by over 30 years of computer monitor usage.
So much so, that I can no longer look at a white or off-white screen with dark text for any considerable time - without severe problems with my vision.
I could not use Construct 2 for a few years, because of this. Only recently have they provided a dark skin theme for their game making interface - thus saving my eyes and making it possible for me to use their application.
Is there a way that the GDevelop user interface colors can be configured with such a dark themed skin?
There are some options in the GDevelop preferences window. There, you can change every colors (of the ribbon and some others). For the controls, you have to use a dark Windows theme.
You can not change the events editor background unfortunately.
I agree that a dark theme would be preferable. Working till late at night can be stresful to the eyes. A dark theme emits much less pixel light and apart of being much cooler, it is also healthier for the eyes.