File manager expand/collapse icon disappear

How can I keep the expand/collapse tree icon ? if I enable prop handlers the icon gone
https://webix.com/snippet/625ccf59

branch mode disables these icons. Other handlers do not affect them.

It was made by design, as collapseAll/expandAll actions will be mishandled when the dynamic branch loading is enabled.
expandAll opens the existing branches at once, but cannot affect folders that were not loaded yet, as loading is an async process.

Can I enable the buttons with an own function?
The function load all the data server side.

Hello @khvde ,
When you use load it’s possible to apply onAfterLoad which fires after data loading is complete and enable buttons
or
use the callback of load method (also it’s possible to use promise)

But how can I enable the button for collapseAll/expandAll? What is the object?