Since SWT 3.1, a new public variable "exclude" was introduced into all
layout data classes such as GridData, FormData and RowData in the layout
package. This new variable is very usefult when you want to use space
occupied by invisible controls. Before 3.1, the space used by invisible
controls are still computed by the layour managers.
I suggest eSWT keeps close compatiable with SWT in this manner.
See the description of the "exclude" field.
/**
* exclude informs the layout to ignore this control when sizing
* and positioning controls. If this value is <code>true</code>,
* the size and position of the control will not be managed by the
* layout. If this value is <code>false</code>, the size and
* position of the control will be computed and assigned.
*
* The default value is <code>false</code>.
*
* @since 3.1
*/
public boolean exclude = false;