Run Time error: Object::connect: No such slot dlgTextScroller::pbPreview_clicked(app)

[jacek]

connect( pbPreview, SIGNAL( clicked() ), this, SLOT( pbPreview_clicked(app) ));

You can't put values, variables and parameter names inside SLOT and SIGNAL macros.

You can store that pointer in a member variable -- there's no point in passing it as a parameter to a method of the same class. Another solution is to use QCoreApplication::instance().