With each release of Windows there are less and less HWND/GDI based applications.

Standard set of HWND/GDI controls (EDIT,COMBOBOX, BUTTON + so called common controls) is not changing since Win95 so it is a dead end.

And in general modern UI tends to move to composition of UI from primitive ctls achieving rich agglomerates. Like in Web UIs:

   <div class="search-input">
     <input type="text" />
     <button />
   </div>

HWND/GDI is really dead for many reasons. Badly scalable on high-DPI, no alpha, no 3D like here: https://sciter.com/sciter-webgl-is-officially-published-in-v... (second screenshot) and no styling/customization.