Avoid to change the alpha channel color value initially set in GAL mode when modifying a color in legacy mode.

pcbnew/class_pcb_layer_widget.cpp

@@ -541,6 +541,15 @@ void PCB_LAYER_WIDGET::ReFill()
 
 void PCB_LAYER_WIDGET::OnLayerColorChange( int aLayer, COLOR4D aColor )
 {
+    // Avoid setting the alpha channel, when we are in legacy mode,
+    // because in legacy mode the alpha channel is not used, but changing it
+    // destroys the GAL color setup
+    if( !myframe->IsGalCanvasActive() )
+    {
+        COLOR4D oldColor = myframe->GetBoard()->GetLayerColor( ToLAYER_ID( aLayer ) );
+        aColor.a = oldColor.a;
+    }
+
     myframe->GetBoard()->SetLayerColor( ToLAYER_ID( aLayer ), aColor );
 
     if( myframe->IsGalCanvasActive() )

pcbnew/pcbnew_config.cpp

@@ -365,13 +365,14 @@ PARAM_CFG_ARRAY& PCB_EDIT_FRAME::GetConfigurationSettings()
 
         // layer colors:
         wxASSERT( DIM( cds.m_LayersColors ) >= PCB_LAYER_ID_COUNT );
+
         for( int i = 0;  i<PCB_LAYER_ID_COUNT;  ++i )
         {
-            wxString vn = wxString::Format(
-                            wxT( "ColorPCBLayer_%s" ),
-                            LSET::Name( PCB_LAYER_ID( i ) ) );
+            wxString vn = wxString::Format( "ColorPCBLayer_%s",
+                                            LSET::Name( PCB_LAYER_ID( i ) ) );
 
-            m_configSettings.push_back( new PARAM_CFG_SETCOLOR( true, vn, LOC_COLOR( i ), cds.m_LayersColors[i] ) );
+            m_configSettings.push_back( new PARAM_CFG_SETCOLOR( true, vn, LOC_COLOR( i ),
+                                        cds.m_LayersColors[i] ) );
         }
 
         m_configSettings.push_back( new PARAM_CFG_SETCOLOR( true, wxT( "ColorTxtFrontEx" ),