[1/3] riched20: Implement handling of WM_KEYDOWN VK_RETURN in a dialog mode.

[Dylan Smith]

> 3. Is there any need for storing the hwndParent in editor.  Couldn't
> the value be obtained by using GetWindowLongW using GWL_HWNDPARENT
> after making sure that editor->hWnd is non-NULL (i.e. windowed mode).
>
Scratch that point, I see that it is tested for using SetParent in the
tests after creating the richedit control.

Other things I noticed:

> +    r = SendMessage(hwRichEdit, WM_GETDLGCODE, (WPARAM)NULL, (LPARAM)NULL);
Avoid superfluous casts.  In this case it is preferred to use 0
instead of casting NULL.  If the cast isn't needed, then leave it out
(See: http://wiki.winehq.org/SuperfluousCasts).

> +struct dialog_mode_messages
> +{
> +    int wm_getdefid, wm_close, wm_nextdlgctl;
> +};
> +
> +static struct dialog_mode_messages dm_messages;
> +
> +static void zero_dm_messages(void)
> +{
> +    dm_messages.wm_close = 0;
> +    dm_messages.wm_getdefid = 0;
> +    dm_messages.wm_nextdlgctl =0;
> +}
Couldn't memset(dm_messages, 0, sizeof(dm_messages)) be used instead
of the special zero_dm_messages function.