Ensure that Enter key presses are never stolen from wxButton in wxMSW.

This commit fixes the following bug: when an in-place editor control containing
an embedded button was used in wxDataViewCtrl, pressing Enter on the button
would close the editor, accepting changes, instead as (generic) wxDataViewCtrl
intercepts WXK_RETURN in its EVT_CHAR_HOOK handler. To prevent this from
happening, wxButton now handles EVT_CHAR_HOOK itself and never lets the parent
window intercept it if it's for WXK_RETURN. To ensure that normal
wxEVT_KEY_DOWN and wxEVT_CHAR are still generated in this case, wxButton
handler calls the new wxKeyEvent::DoAllowNextEvent() method that was added to
allow suppressing EVT_CHAR_HOOK only, without affecting the subsequent events.
DoAllowNextEvent() is currently only used in wxMSW but support for it was also
added to wxGTK and (both) wxOSX ports.

See #9102.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@69984 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/button.cpp

@@ -62,6 +62,10 @@
 // macros
 // ----------------------------------------------------------------------------
 
+BEGIN_EVENT_TABLE(wxButton, wxButtonBase)
+    EVT_CHAR_HOOK(wxButton::OnCharHook)
+END_EVENT_TABLE()
+
 // ============================================================================
 // implementation
 // ============================================================================
@@ -370,6 +374,25 @@ void wxButton::Command(wxCommandEvent & event)
 // event/message handlers
 // ----------------------------------------------------------------------------
 
+void wxButton::OnCharHook(wxKeyEvent& event)
+{
+    // We want to ensure that the button always processes Enter key events
+    // itself, even if it's inside some control that normally takes over them
+    // (this happens when the button is part of an in-place editor control for
+    // example).
+    if ( event.GetKeyCode() == WXK_RETURN )
+    {
+        // We should ensure that subsequent key events are still generated even
+        // if we did handle EVT_CHAR_HOOK (normally this would suppress their
+        // generation).
+        event.DoAllowNextEvent();
+    }
+    else
+    {
+        event.Skip();
+    }
+}
+
 bool wxButton::MSWCommand(WXUINT param, WXWORD WXUNUSED(id))
 {
     bool processed = false;