GUI_MarkupUnselect
Connection callback that is called when a selected markup is unselected.
Callback Parameters
- Markup: Markup object.
Markup {
    type: number; // Markup type
    subtype: number; // Markup subtype
    alternative: number; // Markup alternative
    color: color; // Markup color
    fontname: string; // Font name
    linewidth: number; // Width of markup object.
}