Divider and cancel button now show in the dialog picker.

The root node of the included gl_root_group is "merge", whose attributes
can not be overriden by any "include" tag since it will be dropped.
All of the children inside gl_root_group have no weight.  This makes
the first object occupy the whole space.  We use a weighted frame layout
to wrap gl_root_group.

Bug: 7016213
Change-Id: I758806848f6af3eff2f7746c6ef949ce639c7f6e