Bug 26109 [Dialogs] Need a FormData version of the button sizing API
The button sizing API in Dialog assumes the developer wants a GridData. We should promote the FormData version in PathVariablesDialog to Dialog.
bundles/org.eclipse.jface/src/org/eclipse/jface/dialogs/Dialog.java
* width of the given number of characters.
 * <p>
 * The required <code>FontMetrics</code> parameter may be created in the 
 * following way:
 * <code>
 * 	GC gc = new GC(control);
 *	gc.setFont(control.getFont());
 *	fontMetrics = gc.getFontMetrics();
 *	gc.dispose();
 * </code>
 * </p>
 *
 * @param fontMetrics used in performing the conversion
 * @param chars the number of characters
 * @return the number of pixels
 * @since 2.0
 */
public static int convertWidthInCharsToPixels(FontMetrics fontMetrics, int chars) {
	return fontMetrics.getAverageCharWidth() * chars;
}
/**
 * Creates a dialog instance.
 * Note that the window will have no visual representation (no widgets)
 * until it is told to open. 
 * By default, <code>open</code> blocks for dialogs.
 *
 * @param parentShell the parent shell, or <code>null</code> to create a top-level shell
 */
protected Dialog(Shell parentShell) {
	super(parentShell);