@jasonhouk
It's like that on my SDS100E as well as SDS200E.
If I go to the first field of F for function, in any display mode, it is as default set to inverted colors of white as background and black as text.
If I edit that field by the T button, or in the menu, it will show that the text are set to white and the B button will show black as the back color, the opposite of what it is actually set to.
If I then change color of T it will instead change the background color. And the same mismatch happens with the B color.
It first looks okay as the function to indicate where the cursor are have not been set to blinking but to instead switch text and background color between each other. But that somehow creates a bug in the firmware so that B and T settings are swapped between each other in edit mode.
Some other fields work as they should but System Name and Favorites have the same issues with B and T color settings that are actually switched between each other. But not always. The F field always has that bug but the two other fields randomly show that color bug.
I would say that in certain fields, F-System-Favorite (haven't found any others), the firmware code are reading what colors the display are currently showing instead of what are set and stored in the memory of the display configuration.
/Ubbe