Add a simple wxSetWindowFont() helper

This function is a just a very thin wrapper for WM_SETFONT, but it's
still better to have it rather than write casts to WPARAM and
MAKELPARAM() in several different places.

Note that this removes the assert for font validity from
wxWindow::SetFont() which really doesn't make much sense (and if we
wanted to have it, it would be better to have it for all ports in
wxWindowBase instead) and was never triggered since more than 20 years
of its existence.

include/wx/msw/private.h

@@ -965,6 +965,12 @@ WXDLLIMPEXP_CORE void wxFillLogFont(LOGFONT *logFont, const wxFont *font);
 WXDLLIMPEXP_CORE wxFont wxCreateFontFromLogFont(const LOGFONT *logFont);
 WXDLLIMPEXP_CORE wxFontEncoding wxGetFontEncFromCharSet(int charset);
 
+inline void wxSetWindowFont(HWND hwnd, const wxFont& font)
+{
+    ::SendMessage(hwnd, WM_SETFONT,
+                  (WPARAM)GetHfontOf(font), MAKELPARAM(TRUE, 0));
+}
+
 WXDLLIMPEXP_CORE void wxSliderEvent(WXHWND control, WXWORD wParam, WXWORD pos);
 WXDLLIMPEXP_CORE void wxScrollBarEvent(WXHWND hbar, WXWORD wParam, WXWORD pos);