QCustomPlot Widget not scalable [SOLVED]

[pencky]

Hey Guys

I am trying to scale the QCustomPlot Widget, but it is not possible.
I have a MainWindow, under it a central Widget and then added a Widget from the Widgetbox.
But this Widget has the size of the mainwindow and I can't scale it. In the property window the geometry settings are also grey.
If I promote it to QCustomPlot Widget I can't scale it either.
Has it to do with a little red circle before the widgetname in the object inspector?
How can I scale it?

[pencky]

Yeah I solved it.
It had something to do with the break layout button in the designer mode.