title: How to use custom widget in Qt-Designer
body: <p>I want to use a custom widget in the GUI-Designer of Qt-Creator IDE.
  So i created a class which inherits from Qt's QWidget. It worked to place
  it on a QMainWindow programaticaly, but have to do my work in the desiger
  where it does not appear as an option in the kist of components.</p>
  
  <p>I googled to find a solution for problem an found an manual on, who guesses, the 
  Qt doc page ( <a href="https://doc.qt.io/archives/qt-4.7/designer-creating-custom-widgets.html" rel="nofollow noreferrer">https://doc.qt.io/archives/qt-4.7/designer-creating-custom-widgets.html</a> 
  and <a href="https://doc.qt.io/archives/qt-4.7/designer-creating-custom-widgets.html" rel="nofollow noreferrer">https://doc.qt.io/archives/qt-4.7/designer-creating-custom-widgets.html</a>).
  I tried to follow it but doesn't work.</p>
  
  <p>Does someone know an other way to do this or can give a hint where i can search
  for problems following this tutorial?</p>
  
  <p>Thanks in advance.</p>
  
  <p>Codierknecht</p>