Don't send wxActivateEvent for minimized windows in wxMSW

Unexpectedly, minimizing the window by clicking on its taskbar icon resulted
in a wxActivateEvent. This broke the focus handling in wxTLW and resulted in
debug messages about ::SetFocus() failure whenever the window was minimized in
this way.

It also seems that other existing code doesn't take into account the
possibility of getting an "active" activation event when the window is
minimized and this doesn't happen in the other ports, so don't send this event
in wxMSW neither.

Closes #17128.

docs/changes.txt

@@ -167,6 +167,7 @@ wxMSW:
 - Avoid bogus assert after calling wxDatePickerCtrl::SetRange().
 - Add solution file for building with MSVS 2014 (Peter Tissen).
 - Correct wxGetOsDescription() for Windows 10 (Tobias Taschner).
+- Don't send wxActivateEvent for minimized windows (bzcdr).
 
 wxOSX/Cocoa:
 

interface/wx/event.h

@@ -3005,6 +3005,11 @@ public:
         a @c wxEVT_ACTIVATE or @c wxEVT_ACTIVATE_APP event.
     @endEventTable
 
+    @note Until wxWidgets 3.1.0 activation events could be sent by wxMSW when
+    the window was minimized. This reflected the native MSW behaviour but was
+    often surprising and unexpected, so starting from 3.1.0 such events are not
+    sent any more when the window is in the minimized state.
+
     @library{wxcore}
     @category{events}
 

src/msw/window.cpp

@@ -4044,9 +4044,19 @@ bool wxWindowMSW::HandleDestroy()
 // ---------------------------------------------------------------------------
 
 bool wxWindowMSW::HandleActivate(int state,
-                              bool WXUNUSED(minimized),
+                                 bool minimized,
                                  WXHWND WXUNUSED(activate))
 {
+    if ( minimized )
+    {
+        // Getting activation event when the window is minimized, as happens
+        // e.g. when the window task bar icon is clicked, is unexpected and
+        // managed to even break the logic in wx itself (see #17128), so just
+        // don't do it as there doesn't seem to be any need to be notified
+        // about the activation of the window icon in the task bar in practice.
+        return false;
+    }
+
     wxActivateEvent event(wxEVT_ACTIVATE,
                           (state == WA_ACTIVE) || (state == WA_CLICKACTIVE),
                           m_windowId,