Ok, using WinAPI means it is not easily theme-able, unless they provide custom set of controls. I assume it is possible to use Qt back-end for Windows as well. I wish Lazarus also supported C++ akin to C++Builder. Pascal is a deal-breaker many.
Custom control set is supported too, and there are multiple alternatives.
Yes, Lazarus has a native Win32/64 widgetset (LCL-Win32) that directly uses the Windows API without Qt dependencies.