define java GridBagLayout

gbag =	new GridBagLayout();	Creates GridBagLayout.
	Must add with GridBagConstraints object (gbc below). Can (carefully) reuse same gbc object.
gbc =	new GridBagConstraints();	Creates a new GridBagConsraints object.
	gbc.gridx = i;	Column, counting from 0. Always start at 0. Don't use default (RELATIVE).
	gbc.gridy = i;	Column, counting from 0. Always start at 0. Don't use default (RELATIVE)..
	gbc.gridwidth = i;	Number of columns wide (default 1).
	gbc.gridheight = i;	Number of rows high (default 1).
	gbc.weightx = d;	Relative horizontal space to allocate if container expands. Default 0.0.
	gbc.weighty = d;	Relative vertical space to allocate if container expands. Default 0.0.
	gbc.fill = fill;	How to expand comp if space larger than preferred size. fill can be GridBagConstraints.NONE, GridBagConstraints.VERTICAL, GridBagConstraints.HORIZONTAL, GridBagConstraints.BOTH.
	gbc.anchor = anch;	If component doesn't fill the space, tells how it should be aligned. anch can be one of these GridBagConstraints constants: CENTER (default), NORTH, SOUTH, NORTHEAST, SOUTHWEST, EAST, WEST, SOUTHEAST, NORTHWEST
	gbc.insets = ins;	Space around component. Eg, gbc.insets = new Insets(10,5,5,10);
	gbc.ipadx = i;	Horizontal padding internal to component. Can be negative!
	gbc.ipady = i;	Vertical padding internal to component. Can be negative!