Bug 137315 [Dialogs] Doubleclickable area to restore dialog size is often very small
bundles/org.eclipse.jface/src/org/eclipse/jface/dialogs/Dialog.java
if (IDialogConstants.OK_ID == buttonId) {
			okPressed();
		} else if (IDialogConstants.CANCEL_ID == buttonId) {
			cancelPressed();
		}
	}
	/**
	 * Notifies that the cancel button of this dialog has been pressed.
	 * <p>
	 * The <code>Dialog</code> implementation of this framework method sets
	 * this dialog's return code to <code>Window.CANCEL</code> and closes the
	 * dialog. Subclasses may override if desired.
	 * </p>
	 */
	protected void cancelPressed() {
		setReturnCode(CANCEL);
		close();
	}
	/**
	 * Returns the number of pixels corresponding to the height of the given
	 * number of characters.
	 * <p>
	 * This method may only be called after <code>initializeDialogUnits</code>
	 * has been called.
	 * </p>
	 * <p>
	 * Clients may call this framework method, but should not override it.
	 * </p>
	 * 
	 * @param chars