code: function handleDocumentMousedown(e) {
    if (e.target !== overlay) { return; }
  
    // Highlight and strikeout annotations are bound to text within the document.
    // It doesn't make sense to allow repositioning these types of annotations.
    let annotationId = overlay.getAttribute('data-target-id');
    let target = document.querySelector(`[data-pdf-annotate-id="${annotationId}"]`);
    let type = target.getAttribute('data-pdf-annotate-type');
  
    if (type === 'highlight' || type === 'strikeout') { return; }
  
    isDragging = true;
    dragOffsetX = e.clientX;
    dragOffsetY = e.clientY;
    dragStartX = overlay.offsetLeft;
    dragStartY = overlay.offsetTop;
  
    overlay.style.background = 'rgba(255, 255, 255, 0.7)';
    overlay.style.cursor = 'move';
    overlay.querySelector('a').style.display = 'none';
  
    document.addEventListener('mousemove', handleDocumentMousemove);
    document.addEventListener('mouseup', handleDocumentMouseup);
    disableUserSelect();
  }
docs: Handle document.mousedown event
  
  @param {Event} e The DOM event that needs to be handled