Double buffer

Hi !
How can I use the double buffer on X11 ?
For the moment, the 'Context::EraseAll()'/'Context::Display()' in a V3d_Viewer/V3d_View is obviously not efficient : there must be a unique method (like 'Update()') to refresh the graphic..

Should I use Visual3d_Viewer/Visual3d_View ? Or V3dView::TransientManagerBeginDraw(), but the return code is 'False' for the use of double buffer. So, the V3d_View::Update(), V3d_Viewer::Update() or V3d_Viewer::Redraw() don't do anything (or they keep the old graphic and add the new one).

Thanks for your suggestions.