Refresh zone layers when copper layers change opacity.

Fixes https://gitlab.com/kicad/code/kicad/issues/7468

pcbnew/tools/pcb_control.cpp

@@ -356,6 +356,10 @@ int PCB_CONTROL::LayerAlphaInc( const TOOL_EVENT& aEvent )
 
         KIGFX::VIEW* view = m_frame->GetCanvas()->GetView();
         view->UpdateLayerColor( currentLayer );
+        view->UpdateLayerColor( GetNetnameLayer( currentLayer ) );
+
+        if( IsCopperLayer( currentLayer ) )
+            view->UpdateLayerColor( ZONE_LAYER_FOR( currentLayer ) );
 
         wxUpdateUIEvent dummy;
         static_cast<PCB_EDIT_FRAME*>( m_frame )->OnUpdateLayerAlpha( dummy );
@@ -382,6 +386,10 @@ int PCB_CONTROL::LayerAlphaDec( const TOOL_EVENT& aEvent )
 
         KIGFX::VIEW* view = m_frame->GetCanvas()->GetView();
         view->UpdateLayerColor( currentLayer );
+        view->UpdateLayerColor( GetNetnameLayer( currentLayer ) );
+
+        if( IsCopperLayer( currentLayer ) )
+            view->UpdateLayerColor( ZONE_LAYER_FOR( currentLayer ) );
 
         wxUpdateUIEvent dummy;
         static_cast<PCB_BASE_FRAME*>( m_frame )->OnUpdateLayerAlpha( dummy );

pcbnew/widgets/appearance_controls.cpp

@@ -2412,7 +2412,7 @@ void APPEARANCE_CONTROLS::OnColorSwatchChanged( wxCommandEvent& aEvent )
     view->UpdateLayerColor( layer );
     view->UpdateLayerColor( GetNetnameLayer( layer ) );
 
-    if( layer < PCB_LAYER_ID_COUNT )
+    if( IsCopperLayer( layer ) )
         view->UpdateLayerColor( ZONE_LAYER_FOR( layer ) );
 
     // Update the bitmap of the layer box