Your problem seems related only to GUI, where is the data ??
I am not sure of the Model View architecture... but can suggest the following pseudo code for ur problem -

Qt Code: 
  1. class MyWindow : public QMainWindow
  2. {
  3.  
  4. 	LabelWidget * m_pLabelWidget;
  5. 	Screen * m_pScreen;
  6.  
  7. 	MyWindow()
  8. 	{
  9. 		connect(m_pLabelWidget,SIGNAL(buttonClicked(QString),this,SLOT(handleButtonClick(QString));
  10. 	}
  11. }
  12.  
  13. void MyWindow::handleButton(QString button)
  14. {
  15. 	if(button == "1")
  16. 	{
  17.               m_pScreen->changeColor(green);
  18.               // pop dialog
  19.               // other things you want to do....
  20.         }
  21. 	else ...
  22. 		...
  23. }
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Hope it helps