Hi,

I have a problem with a scroll area for a QWidget when contents get
changed dynamically, e.g,., added to that QWidget after the setWidget
call for the QScrollArea. Instead of a lengthy explanation, here is a
simple example:

Qt Code: 
  1. --- Example.cpp ---
  2. #include <QApplication>
  3. #include <QWidget>
  4. #include <QGridLayout>
  5. #include <QPushButton>
  6. #include <QScrollArea>
  7.  
  8. int main(int argc, char *argv[])
  9. {
  10.   QApplication app(argc, argv);
  11.   QWidget *test = new QWidget;
  12.   QScrollArea area(0);
  13.   area.setWidget(test); // A
  14.   QGridLayout gl(test);
  15.   gl.setSpacing(0);
  16.   gl.setMargin(0);
  17.   QPushButton b0("1", test);
  18.   gl.addWidget(&b0,0,0);
  19.   QPushButton b1("2", test);
  20.   gl.addWidget(&b1,0,1);
  21.   QPushButton b2("3", test);
  22.   gl.addWidget(&b2,1,0);
  23.   QPushButton b3("4", test);
  24.   gl.addWidget(&b3,1,1);
  25.   QPushButton b4("5", test);
  26.   gl.addWidget(&b4,2,0);
  27.   QPushButton b5("6", test);
  28.   gl.addWidget(&b5,2,1);
  29.   // area.setWidget(test); // B
  30.   area.show();
  31.   return app.exec();
  32. }
  33. --- Example.cpp ---
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If I first call setWidget() to put the widget into the QScrollArea and
then add sub-widgets, e.g., QPushButtons then the QWidget displayed in
the QScroll area is empty. Everything works fine if I comment out the
setWidget() call marked "A" and call setWidget() at location"B". However,
I do have a set up where I want to make changes to the QWidget based
on user interaction where it is no longer an option to do the
setWidget() call after changes. Is there a proper way to notify the
QScrollArea about the fact that the QWidget it contains has changed?

Thank you for any help