Thanks for replying.
Hm... comparing the two screenshots again, I see that the most components are found in both: label, groupbox, editbox, combobox, button, radio button, checkbox etc.
The only notable difference in controls probably is the table in bottom left of the advanced dialog. So I assume that table cannot be switched to dark theme. Making the dialog dark would probably result in a mostly dark dialog with a single white control on it. Unless you would switch to another custom component that has the same functionality and more, allowing dark theme?