BlackBox Framework Center

You ask the wrong question. There is no probelm about the Aux window.
Yes, there is a styling problem with Windows 10.
The head line of the main windows changed from blue to white.

Inside BlackBox only the main window and the forms following the new style (white header).
All other windows following the old style (blue header).

With the white header the bound of the window is hard to see. The bound is easier to see with the blue header.

- Helmut

In Windows 10 the color for the title bars can be configured.
By choosing an appropriate theme or the option for displaying title bars in color
BB dialogs will use a colored title.
The color for the document window titles (texts and forms) in BB are also dependent on
the theme but as far as I see cannot be changed easily.

Thanks Josef,
the problem is solved. See https://www.youtube.com/watch?v=sH8KC-keC5U
In the early days of Windows 10 there was no chechbox for switching on the color in the headline.
Now it is available.
- Helmut

Helmut, hard to understand German for me... does it possible to change the style of the MDI headlines?

In Win10 you can personalize some display options.
I don't know exactly how they are called in english because I have a german Win10.
Use Mouse-right on the desktop and choose something like "Settings" (bottom most menu item)
Then choose "Colors" in the left column and switch on "Colors on start page, task bar, title bar ...".