#16 Segfault when resetting parameters before showing preview.

[Paul Richter]

If fgrun is started without properly defined parameters for FG_ROOT or Executable (thus initially bringing up the Select Paths panel), and then Defaults -> Reset is selected, a segmentation fault occurs. The line causing the fault is preview->make_current() in WIzard::reset_settings(). Segfault doesn't occur if the aircraft preview has been displayed (which it normally does when FG_ROOT and Executable are defined).

Likely it's because the Fl_OSG view, though created and initialized, has not been displayed yet so has some unitialized data.