When using renderCB to render elements, custom drag handles are not functioning as expected. The drag functionality remains bound to the default .grid-stack-item-content instead of the specified custom handle.

Environments where issue occurs:

1. HTML with lazyLoad: true (Works fine when lazyLoad: false)
2. React (Doesn't work even with lazyLoad: false, likely due to React components mounting after GridStack initialization)

Expected Behavior:
The custom drag handle should be functional when specified in the renderCB implementation.

Current Behavior:
The drag functionality remains bound to .grid-stack-item-content instead of the custom handle.

[Please let me know if you need any additional information or specific code examples to reproduce the issue.]