You can see this example at: C:\MiniGUI\SAMPLES\BASIC\TaskDialogs\ShowMessage. Thanks Grigory and P.Chornyj.
I like a simple button for expading/hide. But there is QMessageBox in QT 5 which shows the expanded text and which I like most because of the use of scrollbars:

You can see this example at: http://doc.qt.io/qt-5/qmessagebox.html
I would rather it be done in C as one more optional element.
MSDN - Task Dialog Reference according at:
https://msdn.microsoft.com/en-us/librar ... s.85).aspx
https://msdn.microsoft.com/en-us/librar ... s.85).aspx
The so used MsgDebug, would look great with ScrollBars.
