Bug 33550 [Dialogs] Dialog should support remembering size and position
There are several dialogs that remember its size and position. Since restore the size and considering screen size and font changes isn't trivial JFace's Dialog class should support remembering and restoring size and position. These would realy ease the task for subclasses. May be you can steel the code from OpenTypeSelectionDialog.
bundles/org.eclipse.jface/src/org/eclipse/jface/dialogs/Dialog.java
*/
    private static final int VERTICAL_DIALOG_UNITS_PER_CHAR = 8;
    /**
     * Returns the number of pixels corresponding to the height 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 convertHeightInCharsToPixels(FontMetrics fontMetrics,
            int chars) {
        return fontMetrics.getHeight() * chars;
    }
    /**
     * Returns the number of pixels corresponding to the given number of
     * horizontal dialog units.
     * <p>