If this is the behavior of the SplitPane, then this is fine. I logged this bug to better understand the SplitPane dividers specification.

I have a Splitpane that contains 2 AnchorPane that have minimal values. The Splitpane respects the minimal values. That is fine.

I then set the dividerPosisions to 0 (or to 100). The SplitPane accepts these values but the divider is not visually at the passed value.

Getting the divider positions in the tick they have been set returns the "wrong" values, getting the divider in the next tick gets you the actual values (in sync with what is displayed).

Is it the expected behavior?

I have attached a TestCase, click twice on the button underneath the SplitPane, the divider vales are displayed on the console. You will observe the desynchro.