Revert "Set DoubleBuffering to reduce flicker"

This reverts commit 106259f6e6.

eeschema/sch_draw_panel.cpp

@@ -197,8 +197,6 @@ void SCH_DRAW_PANEL::OnShow()
         if( frame )
             frame->ActivateGalCanvas();
     }
-
-    m_parent->SetDoubleBuffered( true );
 }
 
 

eeschema/sch_preview_panel.cpp

@@ -87,8 +87,6 @@ SCH_PREVIEW_PANEL::~SCH_PREVIEW_PANEL()
 
 void SCH_PREVIEW_PANEL::OnShow()
 {
-    m_parent->SetDoubleBuffered( true );
-
     //m_view->RecacheAllItems();
 }
 

gerbview/gerbview_draw_panel_gal.cpp

@@ -100,7 +100,6 @@ void GERBVIEW_DRAW_PANEL_GAL::OnShow()
 
     if( frame )
     {
-        m_parent->SetDoubleBuffered( true );
         SetTopLayer( frame->GetActiveLayer() );
         auto& displ_opts = frame->GetDisplayOptions();
         static_cast<KIGFX::GERBVIEW_RENDER_SETTINGS*>(

pcbnew/pcb_draw_panel_gal.cpp

@@ -416,7 +416,6 @@ void PCB_DRAW_PANEL_GAL::OnShow()
 
     if( frame )
     {
-        m_parent->SetDoubleBuffered( true );
         SetTopLayer( frame->GetActiveLayer() );
         KIGFX::PAINTER* painter = m_view->GetPainter();
         auto settings = static_cast<KIGFX::PCB_RENDER_SETTINGS*>( painter->GetSettings() );