Ensure that we accept WXK_XXX in RegisterHotKey() in wxMSW

RegisterHotKey() wrongly expected to be given VK_XXX MSW virtual key
code constant, which couldn't work in portable code, so fix it to accept
WXK_XXX constants, while preserving compatibility by still accepting
VK_XXX values not clashing with them.

src/msw/window.cpp

@@ -7510,6 +7510,21 @@ bool wxWindowMSW::RegisterHotKey(int hotkeyId, int modifiers, int keycode)
     if ( modifiers & wxMOD_WIN )
         win_modifiers |= MOD_WIN;
 
+    // Special compatibility hack: the initial version of this function didn't
+    // use wxMSWKeyboard::WXToVK() at all, which was wrong as the user code is
+    // expected to use WXK_XXX constants and not VK_XXX ones, but as people had
+    // no choice but to use the latter with the previous version of wxWidgets,
+    // now we have to continue accepting VK_XXX here too. So we assume that the
+    // argument is a VK constant and not a WXK one if it looks like this should
+    // be the case based on its value. It helps that all of WXK constants
+    // before WXK_START have the same value as the corresponding VK constants,
+    // with the only exception of WXK_DELETE which is equal to VK_F16 -- and we
+    // consider that the latter is unlikely to be used.
+    if ( keycode >= WXK_START || keycode == WXK_DELETE )
+        keycode = wxMSWKeyboard::WXToVK(keycode);
+    //else: leave it unchanged because it looks like it's a VK constant (which
+    //      includes ASCII digits and upper case letters)
+
     if ( !::RegisterHotKey(GetHwnd(), hotkeyId, win_modifiers, keycode) )
     {
         wxLogLastError(wxT("RegisterHotKey"));