TCurvyPanel Color was not applied

using Delphi 10.4 Sydney, CurvyControl v1.2.2.0

Changing TCurvyPanel's [Color][BorderColor] in property dose not apply in design mode.

I could not reproduce this.

Your example doesn't seem to be Delphi 10.4. 

I tried reinstalling 'Delphi 10.4' and 'VCL UI Pack' , but it is the same problem.

Look at this :

Google Photos

We were able to reproduce  this issue. This is a problem in 10.4 Sydney with the new implementation for VCL styles in design-time where they now use 'Windows10' for the standard style in design-time.
Just in case you want to change the code yourself, in run-time the name 'Windows' is still used.

We will update our code and the fix will be implemented in the following TMS VCL UI Pack update.

I think I have the same problem with advpolypager. My old style from the Rad Studio 10.3 project is not loaded, and when I change it to the standard one and save the project when I open the project with a new one, the saved style is not loaded. Could you please check that ?

Am I correct that you are referring to the colors of the list that aren't correctly shown?
Or do you have another problem?

Yes, I have issue with colors

Can you please provide more details?
What color settings do you choose and what exactly is going wrong with these color settings?

I opened my project and saw that style settings from ADVPolypager are changed.

Then I changed it back
Compiled and saved works fine
Next day I reopened my Rad Studio 10.4 Sydney and saw that styles were not loaded
I compare .dfm files from my form without style and after I changed it, no difference was found.
P.S.: I saw the same problem by ADVOfficePager by my cooworker project. I will test it and report it here. When I can reproduce it.

If you want to use a specific style for the complete TAdvPolyPager, it is best to use the UIStyle property of the TAdvPolyPager.

An update for the specified UIStyle will be implemented in the upcoming release.

We do notice another problem with the use of the item colors when the UIStyle property is set to tsCustom, this is something that we will investigate further.