allow a spacer with an up and down icon between 2 widgets in a WBoxLayout
Allow a spacer with an up and down button between 2 widgets in a WBoxLayout (a spacer comparable to the one used to resize a widget in a WBoxLayout).
By default the up button should show the item next to the spacer, and the down button should hide the item next to the spacer. However, it should be possible to override this default behaviour (maybe by providing access to these buttons in the WBoxLayout API?).