Pcbnew, drawing sheet: use "First Page" option to draw/plot it.

Some items can be drawn only on the first page or only on the other pages.
a board has only a first page.

pcbnew/dialogs/panel_pcbnew_color_settings.cpp

@@ -483,7 +483,7 @@ void PANEL_PCBNEW_COLOR_SETTINGS::createPreviewItems()
     m_page->SetWidthMils( 6000 );
 
     STRING_LINE_READER reader( g_previewBoard, "preview" );
-    PCB_PLUGIN             pi;
+    PCB_PLUGIN         pi;
 
     try
     {
@@ -499,6 +499,7 @@ void PANEL_PCBNEW_COLOR_SETTINGS::createPreviewItems()
 
     DS_PROXY_VIEW_ITEM* drawingSheet = new DS_PROXY_VIEW_ITEM( (int) IU_PER_MILS, m_page, nullptr,
                                                                m_titleBlock );
+    drawingSheet->SetIsFirstPage( true );
     drawingSheet->SetColorLayer( LAYER_DRAWINGSHEET );
     m_preview->SetDrawingSheet( drawingSheet );
 

pcbnew/pcb_edit_frame.cpp

@@ -483,6 +483,9 @@ void PCB_EDIT_FRAME::SetPageSettings( const PAGE_INFO& aPageSettings )
                                                                m_pcb->GetProject(),
                                                                &m_pcb->GetTitleBlock() );
     drawingSheet->SetSheetName( std::string( GetScreenDesc().mb_str() ) );
+    // A board is not like a schematic having a main page and sub sheets.
+    // So for the drawing sheet, use only the first page option to display items
+    drawingSheet->SetIsFirstPage( true );
 
     BASE_SCREEN* screen = GetScreen();