I'm currently working on a Win32 program which requires a main window containing many child window controls - buttons, listviews and so on. I believe the standard way to build such a window is to first call CreateWindow for the main window, then again for each of the controls.
As an easier option, I'm considering designing the main window using the resource editor's dialog box designer, then using CreateDialog to build the main window in one go.
By using a CLASS statement in the dialog box template, I should be able to get the main window to use a custom window class (and hence a custom window procedure) and thus avoid the window having any dialog-like behaviour. An example of this technique can be found in Charles Petzold's "Programming Windows": the HEXCALC program in chapter 11.
Are there any downsides to creating my main window in this way? If so, what are they? If not, why is this approach rarely used?
The only downside of CreateDialog I know of (as compared to repeated CreateWindow, not talking about some heavyweight framework, just Win32 vs Win32) is that dialog resources position child windows using dialog units. So the layout is dependent not only on DPI, but also on the user's theme settings (choice and size of font).
If any of your controls need to have fixed sizes in terms of pixels, you won't be happy with the dialog-provided positioning and will need to go through and move all the child windows after the fact.
So yes, you can use CreateDialog as a shortcut for creating a bunch of windows with specified classes and styles. But no, you can't do your layout in the dialog editor.
OTOH, you could store the DLU <-> pixel conversion used on your design machine, and then learn enough about parsing the DIALOG resource internal format to pull out the positioning information, then convert to pixels and correct the positioning in more automated fashion.