Bug 73027 [Dialogs] Buttons are too high
I20040831 Buttons are no longer oval but have a rounded rectangle shape (see first screenshot). The second screenshot shows how buttons using the small system font should look like.
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/FontFieldEditor.java
return previewer.getPreferredExtent();
    }
    /**
     * Returns the preview control for this field editor.
     *
     * @return the preview control
     */
    public Control getPreviewControl() {
        if (previewer == null)
            return null;
        return previewer.getControl();
    }
    /**
     * Returns the value control for this field editor. The value control
     * displays the currently selected font name.
     * @param parent The Composite to create the viewer in if required
     * @return the value control
     */
    protected Label getValueControl(Composite parent) {
        if (valueControl == null) {
            valueControl = new Label(parent, SWT.LEFT);
            valueControl.setFont(parent.getFont());
            valueControl.addDisposeListener(new DisposeListener() {
                public void widgetDisposed(DisposeEvent event) {
                    valueControl = null;
                }
            });
        } else {
            checkParent(valueControl, parent);
        }