Warnings when creating ui_TabularCreateUi.h

[Jean-Marc Lasgouttes]

Hello,

With today's build, I get the following warning. Juergen, is this 
related to your recent changes?

JMarc

  GEN    ui_TabularCreateUi.h
../../../../master/src/frontends/qt4/ui/TabularCreateUi.ui: Warning: 
Z-order assignment: 'layoutWidget' is not a valid widget.
../../../../master/src/frontends/qt4/ui/TabularCreateUi.ui: Warning: 
Z-order assignment: 'layoutWidget' is not a valid widget.
../../../../master/src/frontends/qt4/ui/TabularCreateUi.ui: Warning: 
Z-order assignment: 'horizontalSpacer' is not a valid widget.