Created attachment 872192 [details]
Screenshot: Both non-stretchable
Setting the vstrechable property of both to 'false' gets rid of that grey
space, but now there is no border between the widgets which looks wrong.
Simply use a VSpacing(1) or VSpacing(2) instead. A VSpacing is not vertically
stretchable by default.
This is explained in great detail at the libyui layout how-to documentation,
but in this case just using VSpacing instead of VStretch will do the trick.