Qt: corectly do the thumbnails for Win7 on Video

Ref #10154
Close #4726

modules/gui/qt4/main_interface.hpp

@@ -175,7 +175,7 @@ private:
     bool                 b_statusbarVisible;
 
 #ifdef _WIN32
-    HWND WinId();
+    HWND WinId( QWidget *);
     HIMAGELIST himl;
     ITaskbarList3 *p_taskbl;
     UINT taskbar_wmsg;

modules/gui/qt4/main_interface_win32.cpp

@@ -27,6 +27,7 @@
 #include "input_manager.hpp"
 #include "actions_manager.hpp"
 #include "dialogs_provider.hpp"
+#include "components/interface_widgets.hpp"
 
 #include <QBitmap>
 #include <vlc_windows_interfaces.h>
@@ -78,13 +79,14 @@
 #define GET_FLAGS_LPARAM(lParam)      (LOWORD(lParam))
 #define GET_KEYSTATE_LPARAM(lParam)   GET_FLAGS_LPARAM(lParam)
 
-HWND MainInterface::WinId()
+HWND MainInterface::WinId( QWidget *w )
 {
 #if HAS_QT5
-    QWindow *window = windowHandle();
-    HWND id = static_cast<HWND>(QGuiApplication::platformNativeInterface()->
-            nativeResourceForWindow("handle", window));
-    return id;
+    if( w && w->windowHandle() )
+        return static_cast<HWND>(QGuiApplication::platformNativeInterface()->
+            nativeResourceForWindow("handle", w->windowHandle()));
+    else
+        return 0;
 #else
     return winId();
 #endif
@@ -168,12 +170,12 @@ void MainInterface::createTaskBarButtons()
         thbButtons[2].iBitmap = 3;
         thbButtons[2].dwFlags = THBF_HIDDEN;
 
-        HRESULT hr = p_taskbl->ThumbBarSetImageList(WinId(), himl );
+        HRESULT hr = p_taskbl->ThumbBarSetImageList(WinId(this), himl );
         if(S_OK != hr)
             msg_Err( p_intf, "ThumbBarSetImageList failed with error %08lx", hr );
         else
         {
-            hr = p_taskbl->ThumbBarAddButtons(WinId(), 3, thbButtons);
+            hr = p_taskbl->ThumbBarAddButtons(WinId(this), 3, thbButtons);
             if(S_OK != hr)
                 msg_Err( p_intf, "ThumbBarAddButtons failed with error %08lx", hr );
         }
@@ -333,7 +335,13 @@ void MainInterface::changeThumbbarButtons( int i_status )
         default:
             return;
     }
-    HRESULT hr =  p_taskbl->ThumbBarUpdateButtons(WinId(), 3, thbButtons);
+
+    HRESULT hr;
+    if( videoWidget && THEMIM->getIM()->hasVideo() )
+        hr =  p_taskbl->ThumbBarUpdateButtons(WinId(videoWidget), 3, thbButtons);
+    else
+        hr =  p_taskbl->ThumbBarUpdateButtons(WinId(this), 3, thbButtons);
+
     if(S_OK != hr)
         msg_Err( p_intf, "ThumbBarUpdateButtons failed with error %08lx", hr );
 }