zoomUndo_btn.setMargin( btn_insets );
zoomUndo_btn.setToolTipText( "Undo the previous zoom operation" );
zoomUndo_btn.setMnemonic( KeyEvent.VK_U );
// zoomUndo_btn.setPreferredSize( btn_dim );
zoomUndo_btn.addActionListener(
new ActionZoomUndo( this, time_model ) );
super.add( zoomUndo_btn );
super.addSeparator( mini_separator_size );
icon_URL = getURL( Const.IMG_PATH + "ZoomOut24.gif" );