Very simple scenario.
I put three buttons into HBox and align to right. And these buttons may be hidden in some cases, but the left one won't occupy the position of the hidden button.
Must I remove this button besides setting visible to false?
sure, you have to remove objects if you want them to be missing missing != invisible
I used to do this always removeChildAt() & addChildAt. Dont know whether we can manage it with setting x & y position its complex...
In addition to visible, check out the IncludeInLayout property