HWNDComponentPeer: Dismiss modals when windows are moved

This change ensures that popup menus will be dismissed when hosted
plugin windows are moved, even when these plugin views are themselves
hosted inside JUCE views, like those used in the AudioPluginHost.

modules/juce_gui_basics/native/juce_win32_Windowing.cpp

@@ -4160,7 +4160,7 @@ private:
 
     void windowShouldDismissModals (HWND originator)
     {
-        if (isAncestor (originator, hwnd))
+        if (component.isShowing() && isAncestor (originator, hwnd))
             sendInputAttemptWhenModalMessage();
     }
 
@@ -4190,6 +4190,7 @@ private:
 
             constexpr UINT events[] { WM_MOVE,
                                       WM_SIZE,
+                                      WM_WINDOWPOSCHANGING,
                                       WM_NCPOINTERDOWN,
                                       WM_NCLBUTTONDOWN,
                                       WM_NCRBUTTONDOWN,
@@ -4198,6 +4199,17 @@ private:
             if (std::find (std::begin (events), std::end (events), info->message) == std::end (events))
                 return;
 
+            if (info->message == WM_WINDOWPOSCHANGING)
+            {
+                const auto* windowPos = reinterpret_cast<const WINDOWPOS*> (info->lParam);
+                const auto windowPosFlags = windowPos->flags;
+
+                constexpr auto maskToCheck = SWP_NOMOVE | SWP_NOSIZE;
+
+                if ((windowPosFlags & maskToCheck) == maskToCheck)
+                    return;
+            }
+
             // windowMayDismissModals could affect the number of active ComponentPeer instances
             for (auto i = ComponentPeer::getNumPeers(); --i >= 0;)
                 if (i < ComponentPeer::getNumPeers())