QtCreator is exhibiting a ugly view, the font is kinda bad, The upper one is QtCreator and the other one is a normal Qt app. I tried to use qtcreator -style cleanlook, but nothing changed. UPDATE ...
I have a code that I used yesterday to generate plots. Today, when I tried to use it (with the same input as yesterday), I get an error: QGtkStyle was unable to detect the current GTK+ theme. ...