Make amGirder invisible in construction mode since it allows placing anywhere in fortress. Print "insufficient power" if placement was blocked due to that, to avoid confusing noobs.
#include <QApplication>
#include "mainform.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
MyWindow *mainWin = new MyWindow;
mainWin->show();
return app.exec();
}