I have just updated to the latest 1.3 version and I can get a fltk window that now initiates across 2 screens , which solves the first bit of the problem.

But if I do this then the glut window is gretaer than 4096 pixels and hangs.  Even though a call to glget returns 8092 for the max glut window size.

In the test subfolder there is a glut prog called fractals. If I start this and then resize the window , it too hangs at the same place.