The TWebCheckListBox is inherited from VCL's TCheckListBox and not TCustomCheckListBox, and therefore unsupported properties are published and exposed in the object inspector. This is quite annyoing. But not only annyoing, it also leads to compiler error: If the TWebCheckListBox component is on a frame component, then Delphi includes the StyleElements property in the inherit-section in the dfm file and gives a compiler error saying identifier not found "StyleElements".
All TMS Web components should be inherited from the TCustomXxxx classes, and unsupported properties not to be published, so this problem will not occur.
I use Delphi 12 and newest version of TMS Web Core.
We will check what we can do with this. Meanwhile, leave such unique VCL settings to default setting so these are not persisted in the DFM.
StyleElements has its default value (and not saved in the frame's dfm). But when TWebCheckListBox is part of a frame used in a form, then also StyleElements are suddenly part of the inherited properties in the form's dfm. The project is originally developed in Delphi 11.3, and I did'nt came up with this problem. But when installing Delphi 12, this came up. If I don't open the source file containing a frame including a webCheckListBox, then the compiler goes through the code with no errors. As soon as I open the file in Delphi and try to compile, then compiling will fail. So I guess this is a Delphi 12 problem. But anyway, it seems like a good idea to inherit from custom classes, so you can leave out unsupported properties.
We fixed this. Next update will address this.