Automatic move splitter the you maximise a windows

Good morning.
I have a small issue that i didn’t find how to resolve.
I have a form with two list box and a splitter in the middle.
The splitter is necessary in order to increase and decrease the size of the list box.
I need during maximisation that the spliter moves on the right according with the resize of the window.
To do that normally you have to set the property in resizing option Move =true.
This properties work perfectly will all the object except splitter.

Attached an example DB.
https://forums.4d.com/4DBB_Main/x_User/21158779/files/30911728.zip

Ciao
Davide