In plugin program, if we generate a class like subclass of QWidget (or QDialog) as following

class mywidget : public QWidget
{

public:
mywidget(QWidget *parent = 0) : QWidget(parent)
{}
~mywidget(){}
};

Then in main program, if we try to use the class as following

mywidget *mw = new mywidget;
mw->show();

it will crash V3D.

Solved by Zongcai Ruan.

Just comment lines of code in v3d_plugin_loader.cpp:

// 100804 RZC: MUST do not unload plug-ins that has model-less dialog
// if (loader->isLoaded())
// {
// loader->unload(); qDebug() << "unload: " <
// }

It has been updated in svn.