It appears one must actually unmount the component, then mount it again, with a new secondaryInitialSize, for the size re-adjustment to be possible from code.
It should be possible to just re-render the component, and change the sizes without Unmounting?
FEATURE REQUEST: Currently panel areas (what you call layout-pane) cannot be resized using code, one must actually drag the separators on the UI.
For example, I expected forcing a re-render for the component to re-adjust initial size.
It appears one must actually unmount the component, then mount it again, with a new secondaryInitialSize, for the size re-adjustment to be possible from code.
It should be possible to just re-render the component, and change the sizes without Unmounting?