zoomOut_btn.setMargin( btn_insets );
zoomOut_btn.setToolTipText( "Zoom Out by 1 level in time" );
zoomOut_btn.setMnemonic( KeyEvent.VK_O );
// zoomOut_btn.setPreferredSize( btn_dim );
zoomOut_btn.addActionListener(
new ActionZoomOut( this, time_model ) );
super.add( zoomOut_btn );
icon_URL = getURL( Const.IMG_PATH + "Home24.gif" );
if ( icon_URL != null )
zoomHome_btn = new JButton( new ImageIcon( icon_URL ) );