Code (Javascript)

function onUpdateVisuals(item: MindFusion.Diagramming.DiagramItem): void
{
    // ...

    item.setTag({ "textBounds": nodeTextRect, "imageBounds": imageRect });
}

// ...

function contains(rect: MindFusion.Drawing.Rect, point: MindFusion.Drawing.Point)
{
    return rect.x <= point.x && point.x <= rect.x + rect.width &&
        rect.y <= point.y && point.y <= rect.y + rect.height;
}

diagram.addEventListener(MindFusion.Diagramming.Events.nodeClicked, (sender, args) =>
{
    const node = args.getNode();
    if (node.getTag())
    {
        let pt = args.getMousePosition() as MindFusion.Drawing.Point;
        let textBounds = node.getTag().textBounds as Rect;
        let imageBounds = node.getTag().imageBounds as Rect;
        if (contains(textBounds, pt))
            window.open("<textUrl>");
        else if (contains(imageBounds, pt))
            window.open("<imageUrl>");
    }

    // ...
});